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An efficient triflic acid catalyzed regioselective alkylation of 5-R-1H-tetrazoles with readily available allylcarboranes is reported. The suggested synthetic procedure allows the formation of a variety of carboranyl-substituted tetrazoles in a good yield under mild conditions. Transformations of newly synthesized carboranyl tetrazoles under UV irradiation were studied. Allylcarboranes as starting materials were prepared via Pd-catalyzed cross-coupling reaction of iodocarboranes with allylmagnesium bromide.

A straightforward approach toward enantioenriched α-substituted α,β-unsaturated δ-lactams is described. Although a considerable number of approaches toward α,β-unsaturated δ-lactams have been reported, there are relatively few examples of enantioenriched α,δ-disubstituted α,β-unsaturated δ-lactams formation. The δ-stereocenter was formed by addition of allylmagnesium bromide to an N-tert-butylsulfinyl imine. The α,β-unsaturated δ-lactam was furnished by ring-closing metathesis. Although Baylis–Hillman chemistry failed on this cyclic compound, introduction of the hydroxyethyl group prior to ring-closing metathesis was successful. A Baylis–Hillman reaction was used to introduce the substituent at the α-position of the α,β-unsaturated lactam.

A copper-catalyzed conjugate addition of Grignard reagents to 1-(N,N-diisopropylcarbamoyloxy)-1-tosyl-1-alkenes led to 1-(N,N-diisopropylcarbamoyloxy)-1-tosyl-2-branched alkanes. Various copper ligands were screened for this reaction. From certain substrates and allylmagnesium bromide, several Josiphos ligands gave low to moderate asymmetric inductions, along with good diastereoselectivity. The stereochemistry of the 1-(N,N-diisopropylcarbamoyloxy)-1-tosyl-2-branched alkanes from this reaction was assigned by comparison with the same products from another synthetic route using chiral pool synthesis and stereoselective lithiation methods.

Cytotoxic pyrido[1,2- e ]purines are readily available from 8,9-diallylpurines by ring-closing metathesis (RCM) followed by oxidation. The 8,9-diallylpurines were synthesized conveniently by addition of allylmagnesium bromide to the corresponding C-8 unsubstituted purines, followed by rearomatization of the adducts.

A synthesis of the C(1)–C(16) fragment of the brysostatins has been developed. Key steps are the stereoselective copper(I) catalysed addition of allylmagnesium bromide to an alkynyl ester, a condensation of a βγ-unsaturated aldehyde with a ketophosphonate, and the formation of the B-ring under mild conditions by stereoselective intramolecular conjugate addition.

The synthesis of (1R,2R,3S,9aR) and (1R,2R,3S,9aS) trihydroxy quinolizidine alkaloids 3a and 3b from D-glucose derived nitrone 4 is described. The key transformation involves the 1,3-addition of allylmagnesium bromide to nitrone 4 that afforded high diastereoselectivity in the presence of TMSOTf. The N-O bond reductive cleavage, N-Cbz protection, ozonolysis, Wittig olefination, lactum formation and reductive amination cascade afforded the target compounds 3a and 3b in good overall yield.

The stereochemical course of the hydride reduction and of the 1,2-addition of allylmagnesium bromide as well as the Normant reagent to 1 has been determined.

Chiral N -phosphonyl homoallylic amines were synthesized by the reaction of allylmagnesium bromide with chiral N -phosphonyl imines. The C 2 -symmetric chiral N -phosphonyl group was optimized for this reaction. Excellent yields and good diastereoselectivities were obtained for eight examples.

A concise total synthesis of enantiopure (+)-preussin (1) from L-phenylalanine (3) is described. The key steps involve i) syn-selective formation of the 1, 2-amino alcohol fragment2, via chelation controlled addition of allylmagnesium bromide toN-Boc-phenylalaninal, and ii) L-selectride® mediated stereoselective reduction of the ketone8 to the alcohol derivative9 with the required stereochemistry for final cyclization. A concise total synthesis of natural (+) preussin has been developed starting from readily available L-phenylalanine. Download : Download full-size image

Compound CpMo( η 3 -C 3 H 5 ) 2 , 3, has been synthesized from CpMoCl 4 and four equivalents of allylmagnesium bromide. While the compound is stable in donor solvents at room temperature, warming in refluxing MeCN induces the formation of 1,5-hexadiene by a metal-mediated allyl-allyl coupling process. Treatment of 3 with Bu t NC at room temperature affords CpMo( η 3 -C 3 H 5 )(Bu t NC) 2 , 4. A similar reduction with presumed allyl radical loss occurs for [CpMo( η 3 -C 3 H 5 )( η 4 -C 4 H 6 )] + , [1c] + , to afford [CpMo( η 4 -C 4 H 6 )(Bu t NC) 2 ] + , 5. Treatment of [1c] + with methyllithium affords two products, the major one (1c) corresponding to the one-electron reduction pathway and the minor one (CpMo( η 3 -C 3 H 5 )( η 3 -C 3 H 4 -1-Et), 6, ca. 4%) corresponding to nucleophilic addition. Protonation of the 1c:6 mixture affords a 2:1 mixture of cis and trans 2-pentene, in addition to propene. The room temperature Cp 2 Fe + PF 6 − oxidation of 3 in MeCN induces the immediate release of 1,5-hexadiene. The oxidation of 3 in Bu t NC gives complexes [CpMo(CNBu t ) 3 ( η 2 −CH 2 CHCH 2 CH 2 CH=CH 2 )] + PF 6 − (7, major) and [ CpMo ( CNBu t ) 4 ] + PF 6 − (8, minor). Finally, the oxidation of 3 in the presence of butadiene, followed by treatment with CD 3 CN, affords a mixture of [ CpMo ( η 3 : η 3 − C 3 H 4 CH 2 CH 2 C 3 H 4 )(CD 3 CN)] + PF 6 − , 9, and [ CpMo ( η 4 − C 4 H 6 )(CD 3 CN) 2 ] + PF 6 − , 10. Thermal decomposition of this mixture affords butadiene and 1,5-cyclooctadiene.

Starting with 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-2,4,6,8-tetrasila-1,3,5,7-tetraoxacyclooctane (Me(CH2CH)SiO)4 as a core molecule, a succession of alternate platinum-catalyzed hydrosilations of all vinyl groups with HSiMeCl2, as well as alkenylation with allylmagnesium bromide, provided the third generation (G3) as divergent growth of siloxane-based dendrimers. The reaction path of the repetitive allylation/hydrosilation cycles is controlled with NMR spectroscopic analyses. Each of the two steps provided quantitative yields of pure dendrimers. We also changed the simple construction of the G3P molecule into materials with special functions, such as by adding phenylethynyl and p-bromophenoxy groups on its periphery.

The infrared spectra of allyl- and methallyl-d 2 -magnesium bromides have two double bond streching bONds, corresponding to C  CH 2 and C  CD 2 groups in equilibrating allylic isomers. The methylene resonances in the 13 C NMR spectra of allylmagnesium bromide and chloride and methallylmagnesium bromide are broadened at low temperatures by an exchange process which appears to be the interconversion between the classical unsymmetrical allytic structures. Analogous changes are seen in the spectrum of 1,3-dimethylallylmagnesium chloride and in the proton NMR spectrum of allylmagnesium bromide. Rate constants and activation parameters for the exchange have been determined from the line broadenings. Unlike the Grignard reagent, the methylene resonances of diallylmagnesium in tetrahydrofuran are not significantly broadened at reduced temperature, and the deuterated reagent does not have two distinct double bond stretching bands in the IR spectrum.

(SR)-(−)-N-[1-(Triethoxymethyl)ethylidene]-p-toluenesulfinamide (2) was synthesized from the addition reaction of triethoxyacetonitrile with MeLi followed by (+)-(R)-d-menthyl p-toluenesulfinate (1R). Sulfinimine 2 underwent complete stereoselective reduction with 9-BBN and addition reaction with allylmagnesium bromide. Optically pure α-amino acids were synthesized from these adducts by simple hydrolysis.

We wish to report on an unusual reactivity of allylmagnesium bromide. This Grignard reagent acts as a reducing agent towards trifluoromethylated ketones. A single electron transfer is suggested to explain the reductive process. By using an excess of allylmagnesium bromide, an exclusive addition reaction is obtained. The stereochemistry of both addition and reduction reactions is discussed.

Anhydrous ytterbium(III) triflate-catalyzed ring opening of aromatic 1,2-epoxides with allyltributyltin in THF results in the formation of bishomoallyl alcohols in excellent yields and with complete regioselectivity. The results are compared with those obtained with allylmagnesium bromide as allylating agent.

A new kind of perfluoroalkyl-containing multifunctional groups compound was designed. Treatment of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (4) with allylmagnesium bromide provided key intermediate 1H,1H,2H,2H-perfluorooctyltriallylsilane (2). Hydroboration followed by oxidation, epoxidation and dihydroxylation of 2 gave perfluoroalkyl-containing multifunctional groups compound 1a, 1b and 1c, respectively.

2-Allyl-1,2-oxaborolane (II), prepared by the reaction of 2-allyloxy-1,2-oxaborolane (I) with allylmagnesium bromide in ether, is an extremely reactive allylborane. This cyclic borinate ester II is a BCCO-type organoborane and can be used as a novel allylborating reagent. As is usual with allylboranes, II can also add smoothly to various ketones or aldehydes, and when followed by deboronation with diethanolamine gives the corresponding homoallylic alcohols IV. The adducts III, formed via a six-centre cyclic mechanism and allylic rearrangement, have been isolated and identified as a kind of 2-alkenoxy-1,2-oxaborolane.

A novel synthesis for sphydrofuran 1 has been developed. Starting with achiral materials the chiral centers of the target molecule were introduced via enzymatic methods as well as via a diastereoselective Grignard reaction. Rabbit muscle aldolase (RAMA)-catalyzed aldol condesation of chloroacetaldehyde 3 with dihydroxyacetone phosphate (DHAP) 4 affords the C-5 skeleton of 5 which was transformed to sphydrofuran 1 and its analogue 10 via a Grignard addition of allylmagnesium bromide followed by a Wacker reaction.

An improved synthesis of (η 3 -C 3 H 5 ) 4 W from W(OPh) 6 , and allylmagnesium bromide is reported. The further reaction with HX (X = Cl, Br) or iodine leads to [(η 3 -C 3 H 5 ) 3 WX] 2 compounds, which in turn react with donor ligands to form the adducts (η 3 -C 3 H 5 ) 3 W(L)X. Treatment of (η 3 -C 3 H 5 ) 3 W(PMe 3 )Cl with RMgX (R = Me, Et) produces the tungsten-alkyl compounds (η 3 -C 3 H 5 ) 3 W(PMe 3 )R.

2,3-Diferrocenyl-1-morpholino- and 2,3-diferrocenyl-1-piperidinocyclopropenylium tetrafluoroborates react with allylmagnesium bromide to give 3-allylidene-1,2-diferrocenylcyclopropene, 1,2-diferrocenylbenzene, 1,3-diferrocenyl-2-morpholino(piperidino)-hexa-1,3,5-trienes and 2,3-diferrocenyl-1-morpholino(piperidino)bicyclo[3.1.0]hex-2-enes.

The selective formation of allylboronic esters via the allylation of trialkylborates using allylmagnesium bromide was found to be temperature dependent. At −78°C, allylmagnesium bromide reacts cleanly with triisopropylborate to provide allyldiisopropoxyborane. The initially formed bromomagnesium allyl triisopropoxyboronate precipates at this temperature prohibiting the formation of more highly allylated products.

Reaction of allylmagnesium bromide with trifluoromethyl oximes is different than with other Grignard reagents. On the other hand, allylmagnesium bromide acted as a reducing agent towards trifluoromethyl ketones. By using an excess of this Grignard reagent, an exclusive addition reaction is obtained. A single electron reaction is suggested to explain the reductive process.

Careful addition of 1,3-dibromopropane to magnesium in Et 2 O yields 1,3-bis(bromomagnesio)propane which is purified via “magnesacyclobutane” . Reactions of with H 2 O, CO 2 , HgBr 2 and Me 3 SnCl are reported. MgBr 2 catalyses the decomposition of to allylmagnesium bromide .

High-resoln. 13C NMR spectra of terminally monodeuterated alkali metal and alk. earth metal allyl compds. confirm earlier structure assignments: allylmagnesium bromide exists in a s-covalent structure, which rapidly and reversibly goes over into its metallomeric mirror-image; allyllithium forms a distorted p-complex; allylpotassium and allylcesium have the shape of perfectly sym. or slightly asym. p-complexes. No NMR spectroscopic evidence is found in THF soln. for the presence of aggregates and mixed aggregates resulting from dimerization or oligomerization of monomeric allylmetal species. [on SciFinder (R)]

a synthesis of 3- O -benzyl-6-deoxy-1,2:7,8-di- O -isopropylidene- l -, glycero - ( 17 ) and - d - glycero - l - altro -octodifuranose ( 20 ) has been achieved starting with 1,2- O - isopropylidene-5- O - p -tolylsulfonyl-β- d -arabinofuranose ( 6 ). Reaction of 3- O -benzyl-1,2- O -isopropylidene-β- l - arabino -pentodialdo-1,4-furanose ( 9 ) with allylmagnesium bromide afforded the epimeric 3- O -benzyl-6,7,8-trideoxy-1,2- O -isopropylidene-α- d - galacto - ( 11 ) and β- l - altro -oct-7-enose ( 12 ); the stereochemistry at C-5 of the compounds was established by the degradation of 12 to the known 2-deoxy- d - ribo -hexitol ( 24 ).Olefin 12 gave S-azido-3- O -benzyl-6,8-dideoxy-1,2- O -isopropylidene- l - glycero -( 14 ) and - d - glycero -β- l - altro -octofuranose ( 15 ), which were photolyzed to the dialdose derivatives 16 and 19 , respectively. Compound 16 was converted into 3- O -benzyl-6- deoxy-1,2:7,8-di- O -isopropylidene- l - glycero - l - altro -octodifuranose ( 17 ) and subsequently into a mixture of methyl glycosides. Similarly, 19 was converted into the d - glycero analog ( 20 ) of 17 . The stereochemistry at C-7 in derivatives 17 and 20 has been tentatively assigned bv use of n.m.r spectroscopy.

α-Oxoketendithioacetals are shown to be useful intermediates for benzoannelation of α-methylene ketones by reactions with allylmagnesium bromide followed by cationic cyclizations of the resulting carbinolacetals.

Conformational isomers 2a (OHa) and 2b (OHe) have been obtained through addition of allylmagnesium bromide to ketone 1 . Due to the highest barriers of inversion known so far [ΔG≠413 = 134.9 kJ/mol ( 2a ) and 136. 9 kJ/mol ( 2b )] both conformers are indefinitely stable at room temperature in solution.

Racemic fridamycin E ( »c -1) was synthesized in two ways: 1. Addition of lithium ∈rt -butyl acetate to ketone 15 followed by ether and ester cleavage to rac -1; 2. Grignard reaction of allylmagnesium bromide with 15 to rac -18 and subsequent ozonolysis, oxidation, methylation, ester and ether cleavage. The enantiomer θt -18 was obtained by Marschalk reaction of 7 with the chiral building block 20 derived from (S)-lactic acid. A similar reaction sequence converted θt -18 to ent -1 thus proving natural fridamycin E to be of (R)-configuration.

A new synthetic route to T-Damasoone 1 starting with methyl-T-dithiocyclogeranate 2 is described. Addition of RMPT was found necessary to perfon the carbophilic addition of allylmagnesium bromide on ditkioester 2. A dienysulfide, 6,6-dimethyl-2-methylene-(l-methylthio-l,3-butadiene)-l-yl cyclohexane 3, resulted from this addition, and not the expected dithioketal. Following a number of described condition, hydrolysis of 3 to T-damascone 1 proved to be unsatisfactory. These initial attempts but showed the necessity for an acidic medium, This finding allowed the development of a new, very mild method of hydrolysis of dienylsulfides to unsaturated ketones.

Allylmagnesium bromide adds to ( E )-1-(trimethylsilyl)-but-1-en-3-ol diastereoselectively. The carbon-magnesium bond of the intermediate adducts reacts with a range of electrophiles to give synthetically useful products.

Imidoyl chlorides react with 3.3–6.0 molar equivalents of allylmagnesium bromide to give substituted 1,6-dienes in 32–67% yields.

The products from the individual reactions of allylmagnesium bromide with 2-styrylpyridine, with 4-styrylpyridine and with α-allylbenzhydrylaniline,rrespectively, were examined, in order to test the possible role of electron-transfer processes both in the addition and elimination steps of Grignard reagent-anil interactions. In contrast with the smooth 11 adduct of the Grignard reagent with the exocyclic double bond of 2-styrylpyridine, the corresponding reaction with 4-styrylpyridine led principally to oligomeric and/or polymeric adducts. Moreover, heating α-allylbenzhydrylaniline in benzene with an excess of the Grignard reagent led to benzhydrylaniline,ssuggestive of C-C bond homolysis. The results, taken together with other information on Grignard reagent-anil interactions, are consistent with a radical mechanism, possibly initiated by electron transfer.

Selenium acts as a bridging ligand between two iron atoms in the novel complex (μ-Se)(η 5 -C 5 H 5 )Fe(CO) 2 ] 2 ( 1 ), obtained in 60% yield from Na + [(η 5 -C 5 H 5 )Fe(CO) 2 ] and Se 2 Cl 2 . 1 displays nucleophilic reactivity towards protic acids (e.g., HBF 4 ·OEt 2 ) and methyl triflate, CF 3 SO 3 CH 3 , thus giving the protonated and methylated ionic species [(μ-SeR)(η 5 -C 5 H 5 )Fe(CO) 2 2 ] + (R = H: 2a , BF 4 salt; R = CH 3 : 2b , PF 6 salt) in quantitative yields. Rapid deprotonation of 2a occurs in the presence of bases such as diethylamine. Analogous protonation and methylation reactions have been observed with the tellurium complex (μ-Te)[(η 5 -C 5 H 5 )Cr(CO) 3 ] 2 ( 3 ); the ionic compounds [(μ-TeH)(η 5 -C 5 H 5 )Cr(CO) 3 2 ]BF 4 ( 4a ) and [(μ-TeCH 3 ) (η 5 -C 5 H 5 )Cr(CO) 3 2 ]PF 6 ( 4a ), respectively, are obtained. In contrast, the electron-deficient tellurium ligand of the manganese complex (μ 3 -Te)[(η 5 -C 5 H 5 )Mn(CO) 2 ] 3 ( 5 ) is neither attacked by Bronsted acids nor by electrophilic methylating agents (e.g., CF 3 SO 3 CH 3 ) but is rather methylated by methyllithium to give the anionic species [(μ 3 -TeCH 3 )η 5 -C 5 H 5 )Mn(CO) 2 3 ] − that can be isolated pure as the PPN + salt 6 .