Search

Flavonoid structures, found in nature or obtained by synthesis, may be very complex. These Recommendations provide a guide for flavonoid aglycone names. This will also allow the construction of the names for their polyglycosylated species with clarity and conciseness. A joint working party of IUPAC/IUBMB members has prepared these recommendations, which establish rules for the general nomenclature of flavonoids, providing examples of acceptable trivial names, and names derived from trivial names, together with semi-systematic and fully systematic names that follow the published IUPAC recommendations.

The article traces the history of the journal Carbohydrate Research from its debut in 1964 and its subsequent evolution to the present day, viewed from the perspective of one of the founding editors who served as a receiving editor until 2005. The concept of an international journal focused on the broad aspects of carbohydrate science found ready acceptance in the research community, and its volumes now serve as a unified archive of a significant proportion of published research data on all molecular aspects of carbohydrates. Changes in the editor line-up over the years are noted, along with the transition to electronic publishing, and the role of key people in the Elsevier Company toward the success of the journal.

Acetylated d -pentose diethyl dithioacetals were coupled by way of 1-bromo-1-ethylthio derivatives with 2,4-bis(trimethylsilyl)thymine to afford diastereomeric pairs of acyclic-sugar nucleoside analogues bearing a thymin-1-yl and an ethylthio group at C-1. Free-radical desulfurization by the action of tributylstannane removed the ethylthio group to afford the corresponding acetylated 1-(1-deoxy- d -pentitol-1-yl)thymines and subsequently the free title compounds in the arabino, lyxo, ribo, and xylo series. Conformations of the intermediates and products were studied in detail and the final products were evaluated for their potential as agents active against plant viruses and rice blast fungus.

1,6-Anhydro-4-deoxy-4-diazo-2,3-O-isopropylidene-β- d -lyxo-hexopyranose (4) is a stable crystalline compound readily accessible by an improved synthetic procedure. It has been used as a model for evaluating the reactivity of the diazo group, when not stabilized by an adjacent carbonyl function, in a rigid chiral matrix. A range of carbene-type, electrophile-promoted, and 1,3-dipolar reactions were evaluated, leading to 4,4′-alkene dimers, 4-deoxy-3-enose and related derivatives, 4,4-dihalo compounds, 4-spirocyclopropane derivatives, 4-spiropyrazole structures, and by skeletal rearrangement, branched-chain anhydropentose structures having a bicyclo[2.2.2] skeleton.

The methyl beta-glycoside of the title sugar, obtained from 2-deoxy-2-fluoro-beta-D-glucopyranose tetraacetate by a sequence with detailed characterization of all intermediates, was converted by acetolysis-bromination into 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl bromide, coupling of which with (7S,9S)-4-demethoxydaunomycinone afforded the 3,4-diacetate of 4-demethoxy-9-O-(2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl)daunomycinone (19). The antitumor-active 19 was converted by way of its 14-bromo derivative into the 14-hydroxy analogue, the antitumor-active 4-demethoxyadriamycinone glycoside 21.

Based on a literature precedent, preparation of methyl 4-azido-3,4,6-trideoxy-3-fluoro-alpha-D-mannopyranoside (18) was attempted via fluorination of methyl 4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-altropyranoside with diethylaminosulfur trifluoride (DAST). Contrary to expectations, the reaction took place with retention of configuration at the site of the fluorination yielding methyl 4-azido-2-O-benzyl-3,4,6-trideoxy-3-fluoro-alpha-D-altropyranoside. Treatment with DAST of methyl 4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-allopyranoside (8), or its 2-(p-methoxybenzyl) analog 9 resulted in fluorination with inversion of configuration at position 3, to give the corresponding 3-deoxy-3-fluoro glucopyranosides 10 and 11, respectively. Accordingly, compound 18 was prepared from 11, by de-p-methoxybenzylation at O-2, followed by inversion of configuration at C-2 in the resulting methyl 4-azido-3,4,6-trideoxy-3-fluoro-alpha-D-glucopyranoside. The 2-O-methyl analog of 18 (19) was prepared by methylation of 18. Compounds 18 and 19 were converted, conventionally, into the 3-fluoro analogs of the terminal determinants of the O-PS of Vibrio cholerae O:1, serotype Inaba and Ogawa, respectively.

Four anthracycline analogs synthesized in our laboratory were evaluated in comparison with adriamycin (doxorubicin) for their growth-inhibitory effect against five human-tumor cell lines, including lung carcinoma, colon adenocarcinoma, breast adenocarcinoma, melanoma, and glioblastoma. The compounds included 4-demethoxy-7-O-(2,6-dideoxy-2-fluoro-- l -talopyranosyl)daunomycinone (2), its 3′,4′-diacetate (1), its 14-bromo derivative 3, and its 14-hydroxy analog, namely 4-demethoxy-7-O-(2,6-dideoxy-2-fluoro-α- l -talopyranosyl)adriamycinone (4). Compounds 1, 2, and 3 showed moderate cytotoxic effect in most of the cell lines, while compound 4 had a strong effect, comparable to or better than that of adriamycin in most of the cell lines.

The field of carbohydrate science, as documented in the 70 volumes of Advances in Carbohydrate Chemistry (and Biochemistry) during the years 1944 through 2014, is surveyed. Subject areas detailed in individual volumes cover a broad range to include fundamental structural studies, synthesis, reactivity, mechanisms, analytical methodology, enzymology, biological and medicinal applications, food technology, and industrial and commercial aspects. The contributions of many prominent research leaders in the carbohydrate field are recorded in biographical memoirs. Stages in the development of internationally accepted systems for naming carbohydrate structures and for their graphical depiction are noted, and indexing questions for retrieval of data are addressed.

3-Deoxy-D-erythro-hexos-2-ulose bis(thiosemicarbazone) (1) acts as a tetradentate ligand of the N2S2 type which forms stable coordination complexes with metal(II) cations. The Cu(II), Pt(II), and Pd(II) chelates (2, 4, and 6, respectively) of 1 were synthesized and characterized by elemental analysis and NMR spectroscopy. The NMR spectra of the Pt complex (4) showed the coupling of H-1 and C-1, C-2 of the bis(thiosemicarbazone) with 195Pt (33.7% naturally occurring), which supports the structure proposed for the chelate. The complexes 2, 4, and 6 were acetylated to give the corresponding tri-O-acetyl derivatives 3, 5, and 7. Elimination of Cu(II) from 3 with hydrogen sulfide afforded 8, the tri-O-acetyl derivative of 1. Preliminary studies have shown antiviral activity of chelates 2, 4, and 6 against poliovirus type 1.

This article reviews recent developments in the methodology for the measurement of anthocyanins that offer several advantages over classical methods of analysis. The use of UV-diode array and mass spectrometric (MS) detectors, with improved methods of liquid chromatography analysis has facilitated identification of these analytes. The use of capillary electrophoresis (CE) analysis of the anthocyanins under acid conditions has significantly increased peak resolution and improved the detection limits by several orders of magnitude. CE offers the advantage of economies of very small sample size, very small solvent consumption, and short analysis times along with the future possibility of being combined with MS detection.

Reversed-phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) in the positive-ion mode was utilized to analyze crude ether extracts from the root bark of Maclura pomifera, a tree known to have a high content of prenylated xanthones and flavanones. Identification of three xanthones and two flavanones was based on their unique mass spectra. Under optimum conditions peaks corresponding to the [MH](+) ion and characteristic fragments for each compound were observed. (1)H NMR data were used to confirm the identities of two xanthones that had the same molecular mass and similar fragmentation patterns. Fragmentation of the analytes was achieved by application of an electrostatic potential at the entrance of the single quadrupole mass spectrometer. The optimum voltage for fragmentation was found to be related to the class of compounds analyzed and, within each class, to be dependent on the structure of the prenyl moiety. Collision-induced pathways consistent with precedent literature describing the MS characterization of similar compounds and with the observed fragmentation patterns are tentatively proposed.

Derivatives of methyl α-glycosides of antigenic determinants of Vibrio cholerae O:1, serotypes Inaba and Ogawa, specifically fluorinated at position 2′ or 4′ have been synthesized by coupling the appropriately fluorinated derivatives of 3-deoxy- l - glycero -tetronic acid with the methyl α-glycosides of perosamine. The compound having the fluorine atom at position 2 was obtained by electrophilic addition of fluorine to the glycal derived from the parent antigenic determinant, serotypes Inaba, using Selectfluor ™ as a fluorination reagent.

Treatment of the 2,3-isopropylidene acetal of the title dithioxyloside with 2,4,5-triiodoimidazole-PPh3 caused replacement of the 4-hydroxyl group by iodine to afford 82% of the 4-axial iodide 6, converted by base into 4-cyanophenyl 2,3-O-isopropylidene-1,5-dithio-beta-D-glycero-pent-3-enopyranoside++ + (8). Acid treatment of 8 gave 87% of the deacetonated glycos-3-ulose, borohydride reduction of which afforded 63% of 4-cyanophenyl 4-deoxy-1,5-dithio-alpha-L-threo-pentopyranoside (3), together with 27% of the 3-axial epimer. The 3-methyl ether of the title dithioxyloside was satisfactorily prepared via 2,4-protection as the cyclic phenylboronate, methylation, and deprotection; alternative strategy via the 2,4-bis(triisopropylsilyl) ether was complicated because of silyl-group migration under methylation conditions.

This study compares conventional solid–liquid extraction, supercritical fluid extraction (SFE), and pressurized fluid extraction (PFE) for their efficiency in extracting xanthones and flavanones from the root bark of the osage orange tree (Maclura pomifera). Seven compounds were extracted from the plant material by solvent extraction at room temperature for 48 h. The same compounds were removed from the root bark by 45- and 35-min extractions using SFE and PFE, respectively, and under optimized conditions, in same or higher yields than those obtained by the conventional 48-h solvent extraction. Although all seven compounds were present in the SFE extracts when only CO2 was used as the fluid, the addition of 20 vol.% methanol (MeOH) to the CO2 proved essential for achieving high yields. Use of SFE with CO2–MeOH also led to the recovery of an additional flavanone from a wet sample of root bark. This flavanone is absent from the conventional solvent extracts and appears in small amounts in the PFE extracts. An optimized LC separation for the analysis of the different extracts is presented, and it is demonstrated that the separation of xanthones and flavanones is considerably improved by the use of deactivated C18 columns in conjunction with a mobile phase containing acetonitrile and a weak organic acid.

The 4,6-benzylidene acetal of methyl 2-deoxy-2-fluoro-α,β- d -glucopyranoside underwent inversion at C-3 via an oxidation–reduction sequence, and treatment of the derived 3-acetate with N -bromosuccinimide in carbon tetrachloride gave methyl 3- O -acetyl-4- O -benzoyl-6-bromo-2,6-dideoxy-2-fluoro-α- d -allopyranoside ( 6 ). Dehydrobromination of 6 and reduction of the resultant 5,6-ene gave the 5-epimer of 6 , which after removal of the ester substituents, afforded the title compound in good overall yield.

The title dithioxyloside 1 , an orally active antithrombotic agent, as its 2,3-isopropylidene acetal, was converted into the corresponding glycos-4-ulose, which served as precursor via reduction to the 4-epimer of 1 and via oximation–reduction to the 4-acetamido-4-deoxy 4-epimer of 1 .

Preparative routes for anomerically specific 1- C -allylation of 2-amino-2-deoxy sugars have been evaluated in a comparative study of various N -substituents and aglycons as precursors for glycosyl radicals that effectively capture an allyl group from allyltributyltin. The crystalline triacetate 4 of 3-(2-acetamido-2-deoxy- α - d -glucopyranosyl)-1-propene ( 6 ) was obtained in 70% yield when 2-acetamido-3,4,6-tri- O -acetyl-2-deoxy- α - d -glucopyranosyl chloride ( 1 ) was treated with allyltributyltin under free-radical conditions, whereas the corresponding bromide 3 led only to an oxazolidine derivative; the β -1-ethylxanthate analogue of 1 gave 4 , but in only 25% yield. The 2-trifluoroacetamido 1-bromide analogue of 1 was also an effective radical source, giving the 2-trifluoroacetamido analogue 8 of 4 in 60% yield. The free amino analogue 7 of 4 was conveniently obtained via the 2- p -methoxybenzylideneamino 1-bromide analogue of 1 . Use of 3,4,6-tri- O -acetyl-2-deoxy-2-phthalimido- β - d -glucopyranosyl bromide as radical precursor allowed stereospecific access to β -1- C -allyl derivatives of the amino sugar. The crystalline galactosamine analogue 12 of 4 was obtained by using the galacto analogue of chloride 1 , but the corresponding manno chloride gave only an oxazoline product. The 1- C -allylated amino sugar derivatives are conformationally more mobile than derivatives not having a 1- C -linked substituent.

The four major anthocyanins present in juice of the blackcurrant (Ribes nigrum) may be completely separated by capillary zone electrophoresis under strongly acidic conditions. The separation, resolution and peak shapes of the anthocyanins are critically influenced by the pH of the running buffer and the presence of an organic solvent. Fused-silica and polyacrylamide-coated capillary columns were evaluated for their ability to resolve the closely migrating analytes. Optimum qualitative separation was achieved on a fused-silica capillary with a phosphate running buffer containing 30% (v/v) acetonitrile at an apparent pH of 1.5.

The field of carbohydrate science, as documented in the 70 volumes of Advances in Carbohydrate Chemistry (and Biochemistry) during the years 1944 through 2014, is surveyed. Subject areas detailed in individual volumes cover a broad range to include fundamental structural studies, synthesis, reactivity, mechanisms, analytical methodology, enzymology, biological and medicinal applications, food technology, and industrial and commercial aspects. The contributions of many prominent research leaders in the carbohydrate field are recorded in biographical memoirs. Stages in the development of internationally accepted systems for naming carbohydrate structures and for their graphical depiction are noted, and indexing questions for retrieval of data are addressed.

Oxidation of the dithioacetal groups in the O -acetylated 5-azido-5-deoxy dibenzyl dithioacetal 3 of D-xylose and that ( 7 ) of D-ribose leads to triazoline derivatives 4 and 8 , the products of sequential oxidation to the bis(sulfones), loss of AcOH between C-1 and C-2 and, spontaneous intramolecular 1,3-dipolar cycloaddition of an azido ketene intermediate. A possible explanation of the observed diastereoselectivity is discussed.

3,4,5,6-Tetra-O-benzoyl-D-glucose diethyl dithioacetal (2) reacts with ethanethiol under acidic conditions to afford 3,4,5,6-tetra-O-benzoyl-2-S-ethyl-2-thio-D-mannose (3), the stereochemistry at C-2 of which has been assigned by chemical conversions on its debenzoylated derivative, the crystalline 2-S-ethyl-2-thio-D-mannose diethyl dithioacetal (4). In the presence of mercuric chloride (1.1 molar equiv), 4 is converted into crystalline ethyl 2-S-ethyl-1,2-dithio-alpha-D-mannofuranoside (5). Complete demercaptalation of 4 affords syrup 2-S-ethyl-2-thio-D-mannopyranose (6), which was characterized as its phenylhydrazone 7 and the crystalline alpha-pyranose tetraacetate 9. Extended treatment of 4 with mercuric chloride and aqueous sodium hydrogencarbonate resulted in isolation of 6, along with its crystalline 2-epimer, 2-S-ethyl-2-thio-beta-D-glucopyranose (10). Remercaptalation of 6 affords the manno diethyl dithioacetal 4 as the major product, whereas similar treatment of 10 yields ethyl 2-S-ethyl-1,2-dithio-alpha-D-glucopyranoside (13). The mechanism of conversion of 2 into 3, as well as the unusually facile interconversion of 2-S-ethyl-2-thio-D-mannose (6) and its D-gluco epimer 10, has been investigated.

Treatment of d-glucose-derived alkene 4 with cyclopentadiene in the presence of a Lewis acid results in the formation of cycloaddition products 8−11. Evidence is presented to show that these 1,6-anhydro sugar−cyclopentadiene adducts do not arise from rearrangement of 4 to isolevoglucosenone (5) followed by cycloaddition but are the result of Lewis acid-catalyzed rearrangement of alkene 4 to acyclic dienophile 12 followed by addition of cyclopentadiene. Major cycloadduct 8 has been utilized as a source of the enantiomerically pure carbocycles 14−25 by manipulation of the alkene and ketone functions and cleavage of the 1,6-anhydro bridge. In the absence of diene, alkene 4 undergoes rearrangement to enone 5 in 32% yield. Reaction of 5 with several dienes results only in the formation of “bottom-face” adducts 10, 11, 28, and 29, and conjugate addition of either HN3 or Me3COOH is found to be completely stereoselective to afford 30 and 31, respectively. Subsequent manipulation of azide 30 leads to precursors of...

This article surveys methods for the enzymatic conversion of starch, involving hydrolases and nonhydrolyzing enzymes, as well as the role of microorganisms producing such enzymes. The sources of the most common enzymes are listed. These starch conversions are also presented in relation to their applications in the food, pharmaceutical, pulp, textile, and other branches of industry. Some sections are devoted to the fermentation of starch to ethanol and other products, and to the production of cyclodextrins, along with the properties of these products. Light is also shed on the enzymes involved in the digestion of starch in human and animal organisms. Enzymatic processes acting on starch are useful in structural studies of the substrates and in understanding the characteristics of digesting enzymes. One section presents the application of enzymes to these problems. The information that is included covers the period from the early 19th century up to 2009.

Summary 5-Azido-2,3,4-tri-O-benzoyl-5-deoxy-D-xylose diethyl dithioacetal (3) undergoes smooth Lewis acid-catalyzed demercaptalation (boron trifluoride etherate/HgO) to afford the unstable aldehydo-azide 4, which in the presence of Lewis acids yields the tribenzoate 6 of the title compound (7) via an apparent intramolecular Schmidt rearrangement.

This article surveys methods for the enzymatic conversion of starch, involving hydrolases and nonhydrolyzing enzymes, as well as the role of microorganisms producing such enzymes. The sources of the most common enzymes are listed. These starch conversions are also presented in relation to their applications in the food, pharmaceutical, pulp, textile, and other branches of industry. Some sections are devoted to the fermentation of starch to ethanol and other products, and to the production of cyclodextrins, along with the properties of these products. Light is also shed on the enzymes involved in the digestion of starch in human and animal organisms. Enzymatic processes acting on starch are useful in structural studies of the substrates and in understanding the characteristics of digesting enzymes. One section presents the application of enzymes to these problems. The information that is included covers the period from the early 19th century up to 2009.

Acyclic trans -2,3-unsaturated aldoheptonate derivatives ( 1–9 ) obtained from d -aldopentoses by Witting chain-extension served as dienophiles for a detailed comparative study of their asymmetric Diels-Alder cycloaddition with cyclopentadiene. Cycloaddition under uncatalyzed thermal conditions gave mixtures of the four possible stereoisomeric norbornene adducts. The endo:exo ratios and the diastereofacial selectivities in the formation of the adducts were determined by NMR spectroscopy and by chemical transformations. The quantitative distribution of adducts as a function of stereochemistry of the dienophile is discussed.

Cycloaddition of cyclopentadiene with a d -arabinose-derived cis -dienophile, methyl ( Z )-4,5,6,7-tetra- O -acetyl-2,32-dideoxy- d - arabino -hept-2-enonate ( 2 ), under thermal conditions gave essentially a single norbornene aduct, isolated crystaline in 81% yield and identified by NMR spectroscopy and X-ray crystallography as methyl ( 5R ,6S)-6- endo -(1,2,3,4-tetra- O -acetyl- d - arabino -tetritol-1-yl) bicyclo[2.2.1]-hept-2-ene-5- endo -carboxylate ( 3 ). The diene adds exclusively from the si -face of the dienophile and give only the endo product. The same sequence starting from l -arabinose gave the enantiomer ( 7 ) of 3 . In contrast, a related cis -dienophile ( 9 ) having a butenolide ring with cyclopentadiene from the opposite ( re ) face giving mainly the endo adduct (5S,6R)-6- endo -(2,3,4-tri- O -acetyl)- d - arabino -tetritol-1-yl) bicyclo[2.2.1]hept-2-ene-5- endo -carboxylic acid 1,4-lactone ( 10 ), isolated crystalline in 70% yield, whose structure was again established by NMR spectroscopy, and firmly consolidated by X-ray crystallography. The minor (11%) product was the exo (5S,6R)isomer 11 . A cis -enonate 14 , analogous to 2 but deoxygenated at the allylic position, showed negligible diastereofacial selectivity ans reacted with cyclopentadiene to give a mixture of all four possible adducts. A 6-membered ring dienophile 16 was also subjected to the same cycloaddition for comparison with the butenolide 9 ; it gave principally the two endo products 17 and 19 in 31 and 38% yields, respectively, accompanied by 12% of a mixture of the two exo products ( 18 and 20 ). The quantitative distribution of cycloaddition products as a function of dienophile stereochemistry is discussed. The high degree of asymmetric induction observed, especially with the readily accesible dienophiles 2 and 7 , providesa valuable route of access to enantiomerically pure tetra- C -substituted cycloalkanes.

The title glycoside undergoes acetonation with 2-methoxypropene to give a 2:1 mixture of the crystalline 2,3- and 3,4-isopropylidene acetals in 94% yield, which upon methylation under controlled conditions followed by deacetonation afforded the respective 4- and 2-monomethyl ethers. The 2,3-acetal underwent reaction with diethylaminosulfur trifluoride to introduce fluorine at C-4 with net retention of stereochemistry, but the 3,4-acetal under comparable conditions underwent migration of the arylthio group to C-2 and fluorination at C-1, with stereochemical retention at both positions.

A convenient preparative route is described for 3-deoxyaldulosonic acids. Glycal precursors are oxidatively converted into 2-deoxyaldonolactones, which react with 1,3-dithian-2-yl anion to afford 1,3-propanediyl dithioacetals of higher 3-deoxyaldosuloses. Deprotection with mercuric salts in wet or dry alcohols gave high yields of the corresponding alkyl aldulosonates. Preparative reaction conditions were optimized and the anomeric configurations of the ketopyranose products were established by 13C NMR.

A series of glycosylated derivatives of benzophenone, benzhydrol, and benzhydril has been synthesized and evaluated for potential activity as venous antithrombotic agents. Studies on structure-activity relationships revealed that compounds having an electron-withdrawing group in the benzhydril or benzhydrol moiety, and specifically those having the beta-D-xylopyranosyl structure in the sugar moiety, were good antithrombotic agents in a rat model of venous thrombosis.

A set of cis -dienophiles ( 2, 6, 9 ) derived from D - or L -arabinose reacts with high yield and stereospecificity to give enantiomerically pure 5,6-disubstituted norbornenes.

The stereochemistry of dehalogenation of 2-halo sugars with tributyltin hydride has been investigated in terms of the influence of steric and conformational effects using deuterium-labeling techniques. Detailed analysis of the results (Tables I-III) demonstrates that the size and orientation of the ring substituents are a determining factor in the stereochemical outcome of the reaction. However, some results can only be explained considering reduction of two equilibrating radical conformers

The chiral norbornene derivative 2 obtained from Lewis acid-catalyzed reaction of an l -arabinose-derived dienophile 1 and cyclopentadiene was oxidized with OsO 4 NaIO 4 to the dialdehyde 3 , a tetrasubstituted cyclopentane. Mild treatment of 3 with [Rh(dppp) 2 ]Cl (dppp = Ph 2 P(CH 2 ) 3 PPh 2 ] ( 4 selectively epimerized the aldehyde adjacent to the methoxycarbonyl group to give the epi-aldehyde 8 . Under more vigorous conditions, this group was decarbonylated to give the monoaldehyde 11 , and more strenuous treatment removed the second aldehyde group to give the didecarbonylated cyclopentane derivative 5 . The structure and optical purity of 5 was confirmed by its transformation into (1 S ,2 S )-cyclopentane-1,2-dicarboxylic acid ( 7 ).

The C 7 acyclic unsaturated-sugar ester 1 , derived from l -arabinose, and its enantiomer serve as convenient dieneophiles for chirality transfer for synthesis of optically pure carbocyclic derivatives through cycloaddition reactions. Reaction of 1 with cyclopentadiene may be controlled to give preparative access to the 5,6-disubstituted norbornene adducts 4a , 5a , and 7a , according to the conditions used. The distribution of the four possible isomeric products from this cycloaddition was quantitated, and the effect of substitutional variation on the precursor dienophile 1 was also examined. Adducts 4a and 5a were transformed into such substituted carbocycles of known absolute configuration as the methyl esters ( 11 and 12 ) of norbornene (bicyclo[2.2.1]hept-2-ene)-6-carboxylic acid and nortricyclane (tricyclo[2.2.1.0 2,6 ]heptane)-3-carboxylic acid in optically pure form, specifically through decarbonylation reactions using RhCl(PPh 3 ) 3 (Wilkinson's complex) and [Rh(dppp) 2 ]Cl[dppp = Ph 2 P(CH 2 ) 3 PPh 2 ]. The optical purity of 12 was established by the use of a chiral lanthanide shift-reagent.

Cyclopentadiene reacts with a D-glucose-derived hex-3-enose derivative to give norbornene derivatives attached at the 2,3-position of a 1,6-anhydrohexose skeleton; although the bicyclic enone isolevoglucosenone is a plausible intermediate in this reaction, the products actually appear to arise through initial cycloaddition to a rearranged acyclic sugar derivative with subsequent generation of the anhydro ring.