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Covering: up to 2022 Quinolizidine alkaloids (QAs) are a class of alkaloids that accumulate in a variety of leguminous plants and have applications in the agricultural, pharmaceutical and chemical industries. QAs are notoriously present in cultivated lupins (Lupinus spp.) where they complicate the use of the valuable, high-protein beans due to their toxic properties and bitter taste. Compared to many other alkaloid classes, the biosynthesis of QAs is poorly understood, with only the two first pathway enzymes having been discovered so far. In this article, we review the different biosynthetic hypotheses that have been put forth in the literature (1988-2009) and highlight one particular hypothesis (1988) that agrees with the often ignored precursor feeding studies (1964-1994). Our focus is on the biosynthesis of the simple tetracyclic QA (-)-sparteine, from which many of the QAs found in lupins derive. We examine every pathway step on the way to (-)-sparteine and discuss plausible mechanisms, altogether proposing the involvement of 6-9 enzymes. Together with the new resources for gene discovery developed for lupins in the past few years, this review will contribute to the full elucidation of the QA pathway, including the identification and characterization of the missing pathway enzymes.

Kinetic resolution provided a highly enantioselective method to access a range of 3-aryl-3,4-dihydro-2H-1,4-benzoxazines using n-butyllithium and the chiral ligand sparteine. The enantioenrichment remained high on removing the tert-butoxycarbonyl (Boc) protecting group. The intermediate organolithium undergoes ring opening to an enamine. The kinetic resolution was extended to give enantiomerically enriched substituted 1,2,3,4-tetrahydroquinoxalines and was applied to the synthesis of an analogue of the antibiotic levofloxacin that was screened for its activity against the human pathogen Streptococcus pneumoniae.

Kinetic resolution of 2‐arylindolines (2,3‐dihydroindoles) was achieved by treatment of their N‐tert‐butoxycarbonyl (Boc) derivatives with n‐butyllithium and sparteine in toluene at −78 °C followed by electrophilic quench. The unreacted starting materials together with the 2,2‐disubstituted products could be isolated with high enantiomer ratios. Variable temperature NMR spectroscopy showed that the rate of Boc rotation was fast (ΔG ≠≈57 kJ/mol at 195 K). This was corroborated by DFT studies and by in situ ReactIR spectroscopy. The enantioenriched N‐Boc‐2‐arylindolines were converted to 2,2‐disubstituted products without significant loss in enantiopurity. Hence, either enantiomer of the 2,2‐disubstituted products could be obtained with high selectivity from the same enantiomer of the chiral ligand sparteine (one from the kinetic resolution and the other from subsequent lithiation‐trapping of the recovered starting material). Secondary amine products were prepared by removing the Boc group with acid to provide a way to access highly enantioenriched 2‐aryl and 2,2‐disubstituted indolines., Asymmetric synthesis of 2‐arylindolines was achieved by kinetic resolution with n‐butyllithium and the chiral ligand sparteine followed by electrophilic quench. The recovered starting materials and the 2,2‐disubstituted products were isolated with high enantiomer ratios. Variable temperature NMR spectroscopy and DFT studies were used to determine the rate of Boc rotation.

The lupin alkaloid sparteine is a well-known chiral diamine with a range of applications in asymmetric synthesis, as well as a blocker of voltage-gated sodium channels (VGSCs). However, there is only scarce information on the VGSC-blocking activity of sparteine derivatives where the structure of the parent alkaloid is retained. Building on the recent renewed availability of sparteine and derivatives we report herein how modification of sparteine at position 2 produces irreversible blockers of VGSCs. These compounds could be clinically envisaged as long-lasting local anesthetics.

Preparation of 2,2-disubstituted azepanes was accomplished from N-tert-butoxy(N-Boc)-2-phenylazepane by treatment with butyllithium then electrophilic quench. The lithiation was followed by in situ ReactIR spectroscopy and the rate of rotation of the carbamate was determined by variable temperature (VT)-NMR spectroscopy and by DFT studies. Most electrophiles add α to the nitrogen atom but cyanoformates and chloroformates gave ortho-substituted products. Cyclic carbamates were formed from an aldehyde or ketone electrophile. Kinetic resolution with sparteine was only poorly selective. Removal of the Boc group promoted cyclization to a homoindolizidine or an isoindolinone.

The reaction of dichlorocadmium(II) and (-)-sparteine (sp) provides two products, [CdCl2(sp)]) (1) and (Hsp)3[Cd2Cl7] (2). The latter represents one of the rare known examples exhibiting an isolated Cd2Cl73− trianion. Both products are formed in the same reaction mixture and single crystals of one of the two products can be obtained selectively by crystallization depending on the co-solvent. The formation and structural characterization of (H2sp)[CdCl4] (3) is also reported, crystallizing with either dichloromethane (3a) or water (3b) as guest molecules.

A general and highly enantioselective arylation of carbamates derived from primary alcohols was developed by combining Hoppe's sparteine-mediated asymmetric lithiation with Negishi cross-coupling. Coupled with Aggarwal's lithiation-borylation sequence, the current method provides a short and divergent access to a variety of enantioenriched secondary and tertiary benzylic alcohols.

(−)-Sparteine has proven itself to be a highly efficient and versatile ligand. However, in recent years it has become difficult to source. In addition the (+)-enantiomer is also not readily available. Here we report a suite of chiral diamines as potential sparteine surrogates. Chiral trans -1,2-diaminocyclohexane is commercially available in both enantiomeric forms and the parent structure can be easily modified. New (and known) chiral diamines have been tested in the asymmetric silylation of N -Boc pyrrolidine, N -Boc piperidine, the α-alkylation of dimethylhydrazones and in the rearrangement of meso -epoxides. While none match the selectivity of the highly evolved natural product, there is certainly potential for this class of diamine ligands to perform in a diverse set of asymmetric transformations.

The well‐established Hoppe–Beak chemistry, which involves enantioselective generation of organolithium compounds in the presence of (−)‐sparteine, was revisited and applied to unprecedented acylations with Weinreb amides to access highly enantioenriched α‐oxyketones and cyclic α‐aminoketones. Recycling of the sustainable solvent cyclopentyl methyl ether, sparteine, and the released Weinreb “amine” [HNMe(OMe)] was possible through a simple work‐up procedure that enabled full recovery of these precious materials. The methodology features a robust scope and flexibility, thus allowing the enantioselective preparation of scaffolds amenable of further derivatization.

Three chiral derivatives of the alkaloid sparteine (bispidines), characterized by the 3,7-diazabicyclo[3.3.1]nonane moiety, were designed as efficient ligands in a number of enantioselective reactions due to their metal coordination properties. A full evaluation of the 3D properties of the compounds was carried out, as the geometrical features of the bicyclic framework are strictly related to the efficiency of the ligands in the asymmetric catalysis. The selected molecules have different molecular complexity for investigating the effects of different chiral groups on the bicycle conformation. We report here a thorough analysis of their molecular arrangement, by NMR spectroscopy, single crystal X-ray crystallography, and computational techniques, which put in evidence their conformational preferences and the parameters needed for the design of more efficient ligands in asymmetric synthetic routes. The results confirmed the high molecular flexibility of the compounds, and indicated how to achieve a control of the chair-chair/boat-chair conformational ratio, by adjusting the relative size of the substituents on the piperidine nitrogens.

Chiral carbon nanoparticles (CCNPs) were developed by surface passivation using the chiral ligand (-)-sparteine or (+)-sparteine (denoted (-)-SP/CNP and (+)-SP/CNP, respectively). The chirality of the prepared CCNPs was demonstrated by circular dichroism and polarimetry and employed as an enantioselective separation platform for representative racemic mixtures.

The effect of organolithium reagent (RLi: R=nBu, iPr, sBu, tBu), solvent (diethyl ether, diethyl ether/THF and MTBE), and stoichiometry on the (-)-sparteine-mediated silylation of 7,8-dipropyltetrathia[7]helicene shows that, unusually, substantially more than 0.5 equivalent of RLi (R=iPr, sBu, tBu) and a large excess of (-)-sparteine (R=nBu, sBu) is often needed to achieve substantial conversions and good ee values. With nBuLi, however, just one equivalent of the organolithium reagent is sufficient to obtain high conversions. Our best results were obtained using the convenient tBuLi/(-)-sparteine adduct with which the need for a high (-)-sparteine/RLi ratio can be avoided. Single- and double-kinetic resolution (KR) procedures give enantiopure samples of 2-trimethylsilyl- and 2,13-di(trimethylsilyl)-7,8-dipropyltetrathia[7]helicene and two-step double-KR combining (-)-sparteine/sBuLi and chiral formamides affords the synthetically valuable 2-formyl-7,8-dipropyltetrathia[7]helicene. This is the first use of (-)-sparteine for the enantioselective lithiation of helicenes and the first report of tBuLi outperforming sBuLi in a (-)-sparteine-mediated procedure.

For decades, (–)-sparteine was a workhorse chemical reagent. The chiral diamine natural product extracted from the seeds of several types of plants had been widely used as a ligand in asymmetric syntheses and as a cocatalyst in ring-opening polymerization reactions. Chemists also studied (–)-sparteine’s potential as a drug. But in 2010, the compound went missing. At first, chemists had trouble buying (–)-sparteine—the supply chain that academic research labs and chemical companies relied on was drying up. Then, the compound was nowhere to be found. After a drought of several years, the reagent is now available again. However, (–)-sparteine remains sparse. And it’s much more costly than it once was. The bottom line is no one, not even chemical companies that advertise selling it, seems to have an answer as to what happened. The case of the missing (–)-sparteine might not have the same cachet as a murder in an Agatha

The glucose-lowering effects of lupin seeds involve the combined action of several components. The present study investigates the influence of one of the main quinolizidine alkaloids, lupanine, on pancreatic beta cells and in an animal model of type-2 diabetes mellitus. In vitro studies were performed with insulin-secreting INS-1E cells or islets of C57BL/6 mice. In the in vivo experiments, hyperglycemia was induced in rats by injecting streptozotocin (65 mg/kg body weight). In the presence of 15 mmol/L glucose, insulin secretion was significantly elevated by 0.5 mmol/L lupanine, whereas the alkaloid did not stimulate insulin release with lower glucose concentrations. In islets treated with l-arginine, the potentiating effect of lupanine already occurred at 8 mmol/L glucose. Lupanine increased the expression of the Ins-1 gene. The potentiating effect on secretion was correlated to membrane depolarization and an increase in the frequency of Ca(2+) action potentials. Determination of the current through ATP-dependent K⁺ channels (KATP channels) revealed that lupanine directly inhibited the channel. The effect was dose-dependent but, even with a high lupanine concentration of 1 mmol/L or after a prolonged exposure time (12 h), the KATP channel block was incomplete. Oral administration of lupanine did not induce hypoglycemia. By contrast, lupanine improved glycemic control in response to an oral glucose tolerance test in streptozotocin-diabetic rats. In summary, lupanine acts as a positive modulator of insulin release obviously without a risk for hypoglycemic episodes.

The use of LiHMDS with equimolar amount of sparteine in toluene results in the formation of enantiomerically enriched γ-lactam, a useful synthon for the synthesis of (R)-(+)-doxapram.

We report the enantioselective, lateral deprotonation of ortho-protected or functionalized tertiary N,N-dialkyl aryl O-carbamates 5-7 (Scheme 2 ) and meta-protected carbamates 14, 15, and 20 (Schemes 5 and 7 ) by s-BuLi/(-)-sparteine and subsequent quench with a variety of electrophiles to give products 11-13 and 16, 17, and 21 in yields up to 96% and enantiomeric ratios up to 99:1. The influence of organolithium reagents, ratio of organolithium/(-)-sparteine pair versus N,N-dialkyl aryl O-carbamate starting materials, temperature, solvents, electrophiles, substituents located ortho or meta to the O-carbamate moiety, and O-carbamate N-substituents was investigated. The identical absolute configuration of the stereogenic center of the major enantiomers of the products, as established by single-crystal X-ray analysis for substrates (S)-11c, (S)-19, and (S)-21a, provides evidence for a consistent stereochemical course in the enantioselective deprotonation. Mechanistic investigations, including an estimate of the configurational stability of the benzyllithium species 9 (starting from 12e; Scheme 8 ) and 23 (starting from 17e; Scheme 9 ), both derived by tin-lithium exchange, and 24 (starting from 20; Scheme 9 ) are reported. The experimental results, together with semiempirical molecular orbital calculations (PM3/SMD), are consistent with a process in which enantioinduction occurs in the deprotonation step (Scheme 11 ).

A hydrogen-bond motif based on a squaramide and sparteine efficiently promoted the ring-opening polymerization of L-lactide at ambient temperature. Narrowly dispersed polymers with precise molar masses (Đ = 1.05, Mn = 16 240 g mol−1) were obtained in a short reaction time (98% conv., 11 h) and with retention of stereochemistry. Experimental data and computational results indicated that the squaramide and sparteine pair is a competent H-bond donor–acceptor catalyst in living polymerization.

Enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione by alkynyllithium reagents prepared from alkynes, n -BuLi, and sparteine gave chiral cis -diols possessing two alkyne moieties with moderate ee. Subsequent Ru-catalyzed [2+2+2] cycloaddition of the diol with alkynes afforded chiral 1,5-dibromotriptycenes.

Helical structures are chiral, which means that if we can synthesize a polymer having a stable one-handed helicity, the polymer is optically active. In 1979, we succeeded in the synthesis of a one-handed helical polymer from an optically inactive achiral monomer, triphenylmethyl methacrylate (TrMA). This is the first example of the asymmetric synthesis of an optically active one-handed helical polymer. The polymer (PTrMA) exhibited an unexpected high chiral recognition ability and afforded a practically useful chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) by coating it on silica gel. In addition, we also succeeded in the development of very useful CSPs for HPLC using the phenylcarbamate derivatives of polysaccharides, cellulose and amylose. These CSPs can efficiently resolve a broad range of chiral compounds, and have been used all over the world for separating and analyzing chiral compounds.

An 8-step, gram-scale synthesis of the (-)-sparteine surrogate (22 % yield, with just 3 chromatographic purifications) and a 10-step, gram-scale synthesis of (-)-sparteine (31 % yield) are reported. Both syntheses proceed with complete diastereocontrol and allow access to either antipode. Since the syntheses do not rely on natural product extraction, our work addresses long-term supply issues relating to these widely used chiral ligands.

The synthesis of a new class of epoxide derivatives from prochiral vinylidene bisphosphonate (VBP) precursors is reported using hydrogen peroxide as the terminal oxidant. The reaction is carried out using a series of possible organic catalysts having a basic character, the best results being observed using quinine and sparteine. These catalysts not only provide from good to excellent epoxide yields with a large variety of VBPs but also interesting enantioselectivities in the 67-96% ee range at least in the case of the Ph and m-MeO-Ph VBP derivatives opening the way to a number of chiral anti-osteoporosis potentially active pharmaceutical ingredients.

The stereoselective reagent-controlled homologation of boronic esters is one of a small number of iteratable synthetic transformations that if automated could form the basis of a veritable molecule-making machine. Recently, α-stannyl triisopropylbenzoates and α-sulfinyl chlorides have emerged as useful building blocks for the iterative homologation of boronic esters. However, α-stannyl benzoates need to be prepared using stoichiometric amounts of the (+)- or (-)-enantiomer of the scarcely available and expensive diamine sparteine; also, these building blocks, together with the byproducts that are generated during homologation, are perceived as being toxic. On the other hand, α-sulfinyl chlorides are difficult to prepare with high levels of enantiopurity and are prone to undergo deleterious acid-base side-reactions under the reaction conditions for homologation, leading to low stereospecificity. Here, we show that the use of a hybrid of these two building blocks, namely, α-sulfinyl triisopropylbenzoates, largely overcomes the above drawbacks. Through either the sulfinylation of α-magnesiated benzoates with either enantiomer of Andersen's readily available menthol-derived sulfinate or the α-alkylation of enantiopure S-chiral α-sulfinyl benzoates, we have prepared a range of highly enantiopure mono- and disubstituted α-sulfinyl benzoates, some bearing sensitive functional groups. Barbier-type reaction conditions have been developed that allow these building blocks to be converted into lithium (t-BuLi) and magnesium (i-PrMgCl·LiCl) carbenoids in the presence of boronic esters, thus allowing efficient and highly stereospecific homologation. The use of magnesium carbenoids allows carbon chains to be grown with the incorporation of sensitive functional groups, such as alkyl/aryl halides, azides, and esters. The use of lithium carbenoids, which are less sensitive to steric hindrance, allows sterically encumbered carbon-carbon bonds to be forged. We have also shown that these building blocks can be used consecutively in three- and four-step iterative homologation processes, without intervening column chromatography, to give contiguously substituted carbon chains with very high levels of enantio- and diastereoselectivity.

Natural products are a prolific source for the identification of new biologically active compounds. In the present work, we studied the in vitro and in vivo antimalarial efficacy and ADME-Tox profile of a molecular hybrid (AM1) between 4-aminoquinoline and a quinolizidine moiety derived from lupinine (Lupinus luteus). The aim was to find a compound endowed with the target product profile-1 (TCP-1: molecules that clear asexual blood-stage parasitaemia), proposed by the Medicine for Malaria Venture to accomplish the goal of malaria elimination/eradication. AM1 displayed a very attractive profile in terms of both in vitro and in vivo activity. By using standard in vitro antimalarial assays, AM1 showed low nanomolar inhibitory activity against chloroquine-sensitive and resistant P. falciparum strains (range IC50 16–53 nM), matched with a high potency against P. vivax field isolates (Mean IC50 29 nM). Low toxicity and additivity with artemisinin derivatives were also demonstrated in vitro. High in vivo oral efficacy was observed in both P. berghei and P. yoelii mouse models with IC50 values comparable or better than those of chloroquine. The metabolic stability in different species and the pharmacokinetic profile in the mouse model makes AM1 a compound worth further investigation as a potential novel schizonticidal agent.

The synthesis of a new class of epoxide derivatives from prochiral vinylidene bisphosphonate (VBP) precursors is reported using hydrogen peroxide as the terminal oxidant. The reaction is carried out using a series of possible organic activators having a basic character, with the best results being observed using quinine and sparteine. These activators not only provide from good to excellent epoxide yields with a large variety of VBPs, but also interesting enantioselectivities in the 67%–96% ee range, at least in the case of the Ph and m-MeO–Ph VBP derivatives, opening the way to a number of chiral anti-osteoporosis potentially active pharmaceutical ingredients.

Four new copper(II)/diamine complexes comprising some (+)-sparteine surrogates and a cyclohexane-derived diamine were prepared and evaluated as chiral catalysts in desymmetrisation of meso-diols and asymmetric Henry reactions. Mono-benzoylation reactions generated two products with high enantioselectivity (90:10 to 97:3 er). Asymmetric Henry reactions gave nitro alcohols in 90:10 to 98:2 er. Notably, the sense of induction with the (+)-sparteine surrogates was opposite to that obtained using the copper(II)/(−)-sparteine complex. One of the nitro alcohol products was utilised in a concise synthesis of a chiral morpholine.

The (+)-sparteine-mediated lithiation–substitution of o-benzyl-N-pivaloylaniline with various ketones was investigated. The obtained highly enantioenriched tertiary alcohols were used for the synthesis of alkenyl-substituted products 12 and 13 as well as 3,3,4-trisubstituted tetrahydroquinoline derivatives 22–24. The reaction with α,β-unsaturated ketones afforded highly enantioenriched 1,4-addition products 28–33 and provided a protocol for the asymmetric synthesis of highly substituted tetralin derivative 34.

The improved performance of the sparteine surrogate compared to sparteine in a range of applications has highlighted the need to develop an approach to the (-)-sparteine surrogate, previously inaccessible in gram-quantities. A multi-gram scale, chromatography-free synthesis of the racemic sparteine surrogate and its resolution via diastereomeric salt formation with (-)-O,O'-di-p-toluoyl-l-tartaric acid is reported. Resolution on a 10.0 mmol scale gave the diastereomeric salts in 33% yield from which (-)-sparteine surrogate of 93 : 7 er was generated. This work solves a key limitation: either enantiomer of the sparteine surrogate can now be readily accessed.

5-Mono- and 5,5-disubstituted tricyclic bispidines, derivatives of the known (+)-sparteine surrogate, have been synthesized in four-to-six steps from the natural alkaloid (–)-cytisine and evaluated as chiral ligands in the enantioselective lithiation/stannylation of an O-alkyl carbamate. Structure–selectivity studies revealed that a small 5-endo substituent is tolerated, whereas larger 5-endo substituents and even small 5-exo substituents lead to significantly reduced levels of chirality transfer.

In the presence of (-)-sparteine or a (+)-sparteine surrogate, organolithiums add to N-alkenyl-N'-arylureas to give benzylic organolithiums in an enantioselective manner. Under the influence of DMPU, these organolithiums undergo rearrangement with migration of the N'-aryl ring from N to C, leading to the urea derivatives of enantiomerically enriched amines bearing tertiary substituents. Basic hydrolysis returns the functionalized amine, providing a new synthetic route to compounds with quaternary stereogenic centers bearing nitrogen.

D 7 Li, 15 N heteronuclear shift correlation through scalar cou- pling has successfully been applied to several lithium organyls consisting of polydentate N ligands such as N,N,N',N'-tetramethylethylenediamine (tmeda), N,N,N',N',N''-pentamethyldi- A (pmdta) and (� )-spar- teine. Structural insights on the confor- mation of benzyllithium·pmdta (5 )i n a toluene solution and the strength of ion pairing in combination with PGSE NMR measurements, 1 H, 1 H- NOESY and 1 H, 7 Li-HOESY experi- ments are presented. By studying in detail the formation of 5 in solution, a transient species has been observed for the first time and assigned to a pre- complex of nBuLi and pmdta. In addi- tion, the solution behaviour of the complex formed between benzyllithium and (� )-sparteine (8) has been studied by PGSE and multinuclear NMR spec- troscopy. The straightforward synthesis and first applications in asymmetric lithiations are also reported, which show that the new system benzyllithi- um·(� )-sparteine (8) provide poorer enantioselective induction than the classical nBuLi·(� )-sparteine (6). The results were supported by deprotona- tion experiments confirming that the formation of 8 relies on two relevant factors, namely temperature and lithi- A reagent. The existence of 8 may thus interfere with the asymmetric in- duction when the system nBuLi· (� )-sparteine is used in the enantiose- lective deprotonations of N-Boc-N-(p- methoxyphenyl)-benzylamine conduct- ed in toluene.

Проведено исследование противогриппозной активности алкалоидов надземной части Chamaecytisus ruthenicus (ракитника русского), собранного в период цветения в предгорьях Южного Урала, в отношении вируса гриппа А/California/07/09(H1N1)pdm09. Компонентный состав тестируемых смесей определяли хромато-масс-спектромет­рическим методом. Цитотоксичность и противогриппозные свойства суммы алкалоидов Ch. ruthenicus и ее фракций были изучены in vitro в культуре клеток MDCK в отношении вируса гриппа А/California/07/09 (H1N1)pdm09, в качестве препарата сравнения использовали римантадин. На основании полученных данных рассчитывали 50% цитотоксическую дозу CTD50, 50% эффективную дозу EC50, а также индекс селективности SI (отношение CTD50 к EC50), характеризующий избирательность действия образца в отношении вируса. Согласно полученным данным наибольшей противогриппозной активностью обладает сумма алкалоидов Ch. Ruthenicus (SI = 77), в которой содержатся мажорные алкалоиды спартеин, 17-оксоспартеин, лупанин, 10,17-диоксоспартеин, и фракция 4 (SI=52), содержащая спартеин и лупанин. Показано, что рассчитанные индексы селективности (SI) для суммы алкалоидов и отдельных фракций ракитника русского значительно превосходят таковые для препарата сравнения римантадин (SI = 5). Этот факт подтверждает перспективность дальнейшего изучения противовирусных свойств индивидуальных алкалоидов Сh. rithenicus с целью поиска новых противогриппозных агентов растительного происхождения., Activity of the four fractions of the total alkaloids of Chamaecytisus ruthenicus (Fabaceae) collected at the flowering period in the South Ural region against influenza virus A (H1N1) was investigated. The componentsof the alkaloid mixtures were identified by GC/MS method. Cytotoxicity and antiflu properties of the sum and fractions of alkaloids Ch. ruthenicus have been studied in vitro (MDCK cells and flu virus of a А/California/07/09(H1N1)pdm09); rimantadin was used as a standard drug. CTD50 (50% сytotoxic dose), EC50 (50% effective dose), and also an index of selectivity SI (relation CTD50 to EC50), characterizing the antiviral action have been calculated. According to the obtained data, the sum of alkaloids Ch. Ruthenicus (major alkaloids – sparteine contain, 17-oksospartein, lupanine, 10,17-dioksospartein) and fraction 4 (major alkaloids – sparteine and lupanine) possess the high antuflu activity (SI = 77 and SI=52). It is shown that the calculated indexes of selectivity (SI) for the sum of alkaloids of Ch. Ruthenicus and its fractions considerably surpass those for a standard drug rimantadin (SI = 5). This fact confirms the perspective of the further studying of antiviral properties of individual alkaloids Сh. rithenicus for the purpose of search new antiflu agents among plant substances.

The enantioselective deprotonation of N,N-diisopropy-1-methylcyclopropanecarboxamide (2) with i-PrLi-(-)-sparteine has been studied at theoretical levels up through B3LYP/6-311+G*. Thirty-six conformationally flexible intermediate complexes involving i-PrLi-(-)-sparteine and 2 were located via geometry optimizations The lowest energy complex would lead to abstraction of the pro-S hydrogen from 2, and several higher energy complexes would lead to loss of the pro-R hydrogen. The lowest energy complex was found to have the lowest activation energy leading to loss of the pro-S hydrogen of 2 as observed experimentally. The results demonstrate that the conformations of the N,N-diisopropyl groups in the amide moiety of 2 have a large effect on the enantioselectivity of the lithiation.

On the basis of literature interpretation of 13 C NMR and 1 H NMR spectra of bis-quinolizidine alkaloids, the values of free enthalpy Δ G of conformational equilibria of those compounds were calculated. The results were analysed together with the X-ray and DFT data to discuss the effects of different substituents attached to the sparteine system in various positions as well as the effects of structural modifications on conformational equilibria. The measure of the effect was expressed by ΔΔ G value, defined as the difference in Δ G of the compound under consideration and its parent compound without a given substituent.

In a simple and convenient way, we have improved the non-chromatographic isolation of optically pure (−)-2-oxosparteine ((−)-lupanine) and (+)-sparteine. The fast and efficient method for the determination of the ee of bisquinolizidine alkaloids has been proposed. A relatively simple simple 1H NMR method has been applied for evaluation of the % ee of enantiomers of the lupanines and sparteines with the chiral dibenzoyltartaric acids as the shift reagents. The 1H NMR spectra of the bases and the new salts in polar solvents have been measured. The results are confirmed by chiral HPLC method. Additionally, for the first time X-ray analysis of the salt of (−)-lupanine has been performed. The improved method of purification of bisquinolizidine alkaloids will considerably facilitate the employment of these alkaloids as chiral ligands in asymmetric reactions and as pharmacological tools.

Short routes to enantiomerically pure indolizidine and quinolizidine alkaloids have been developed using imino-aldol reactions of enolates derived from phenyl 5-chlorovalerate. High levels of syn selectivity (dr ∼13-16:1) were obtained using lithium enolates of phenyl esters in combination with tert-butylsulfinyl imines. The imino-aldol adducts were deprotected and cyclized to afford (-)-epilupinine ((-)-2) and (-)-tashiromine ((-)-1) in two further steps.

A comprehensive study of the enantioselective Pd-catalyzed α-arylation of N-Boc pyrrolidine has been carried out. The protocol involves deprotonation of N-Boc pyrrolidine using s-BuLi/(-)-sparteine in TBME or Et(2)O at -78 °C, transmetalation with ZnCl(2) and Negishi coupling using Pd(OAc)(2), t-Bu(3)P-HBF(4) and the aryl bromide. This paper reports several new features including in situ React IR spectroscopic monitoring of the process; use of (-)-sparteine and the (+)-sparteine surrogate to access products with opposite configuration; development of a catalytic asymmetric lithiation-Negishi coupling reaction; extension to a wide range of heteroaromatic bromides; total synthesis of (R)-crispine A, (S)-nicotine and (S)-SIB-1508Y via short synthetic routes; and examples of α-vinylation of N-Boc pyrrolidine using vinyl bromides exemplified by the total synthesis of naturally occurring (+)-maackiamine (thus establishing its configuration as (R)). In this way, the full scope and limitations of the methodology are delineated.

An efficient and inexpensive protocol for the Sonogashira-type cross coupling reactions of phenylacetylenes with a variety of haloarenes including activated aryl chlorides employing the structurally well-characterized bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyst is described.

This article addresses the mechanistic features of asymmetric car- bolithiation of b-methylstyrenes. While often the presence of functional groups is required to obtain high enantioselec- tivities in carbolithiation reactions, simple b-methylstyrene also gives high selectivities in ()-sparteine-mediated addition of alkyl lithium compounds. Computational studies on the carboli- thiation of b-methylstyrene with ()- sparteine show that the observed selec- tivities are the result of repulsion ef- fects in the diastereomeric transition states between the ()-sparteine·alkyl lithium adduct and the b-methylstyr- ene, upon approximation of the two re- actants. In contrast, for the ortho- amino b-methylstyrene (E)-benzyl(2- propenylphenyl)amine (4) X-ray struc- ture analyses of intermediate lithium amides indicate a carbolithiation mech- anism in which one side of the double bond is shielded by the amide moiety, leaving only one side free for approach of the chiral alkyl lithium adduct.

In this perspective we discuss the recent developments of stereoselective synthesis of substituted pyridines, piperidines, and piperazines from cheap and commercially readily available starting materials. Pyridine N-oxides and pyrazine N-oxides are reacted with alkyl, aryl, alkynyl and vinyl Grignard reagents to give a diverse set of heterocycles in high yields. Optically active substituted piperazines are obtained by an asymmetric reaction from pyrazine N-oxides using sparteine as chiral ligand. In addition, a stereoselective synthesis of dienal-oximes from the reaction between pyridine N-oxides and Grignard reagents is presented, which results in a useful intermediate for the synthesis of a diverse set of compounds.

Total synthesis of (+)-epilupinine was accomplished in nine steps and in 48% overall yield, in which INOC was used as the key step for the construction of the quinolizidine skeleton. We found that it was an extremely difficult task to prepare the key intermediates (R)-N-(3-nitropropyl)-2-vinylpiperidine or (R)-(2-vinylpiperid-1-yl)propanal by routine methods. Thus, by using Fukuyama's oxime synthesis, a general method was developed for highly efficient conversion of 3-(N,N-dialkylamino)propanols into 3-(N,N-dialkylamino)propanal oximes without using the corresponding aldehydes.

The use of structurally well-defined chiral [CuCl 2 (sparteine)] 1 and [NiCl 2 (sparteine)] 2 complexes as catalysts under fluoride anion-promoted double catalytic activation (DCA) conditions cause enantioreversal in the asymmetric Mukaiyama aldol reaction of 1-phenyl-1-trimethylsiloxyethylene with various aromatic aldehydes. A similar enantioreversal also occurs in the direct aldol reaction between methyl vinyl ketone and various aromatic aldehydes under Et 3 N promoted DCA conditions. We have quantitatively analyzed using group theoretical analysis via symmetry deformation coordinates, the molecular structures of 1 and 2 from the X-ray structural data; the results from the study show that the innate stereochemical differences that are present in their molecular structures, form the basis for the enantioreversal phenomenon in the asymmetric C–C bond-forming aldol reactions.