Jeanine Cleophax

Asymmetric synthesis of 1,3,4-trisubstituted and 3,4-disubstituted 2-azetidinones: strategy based on use of D-glucosamine as a chiral auxiliary in the Staudinger reaction

An efficient asymmetric approach to the synthesis of trisubstituted azetidin-2-ones is presented. The strategy relies on the use of ketene–imine cycloaddition between ketenes generated from phthalimidoacetic and methoxyacetic acids and a chiral Schiff base (3) derived from 3,4;5,6-di-O-isopropylidene-D-glucosamine propane dithioacetal (2) and cinnamaldehyde; the removal of the chiral auxiliary group by β-elimination is a noteworthy facet of this communication.

Some ring-opening reactions of a diepoxide derived from (−)-quinic acid

Abstract A useful preparative route to nitrogen-containing, carbocyclic derivatives is described from (−)-quinic acid. (−)-Quinic acid was converted via the 3,4- O -cyclohexylidene-lactone into 1- L -3- O -tosyl-5- C -tosyloxymethylcyclohexane-1,2,5/3-tetrol ( 5 ) by sequential reduction with sodium borohydride, toluene- p -sulphonylation, and acid hydrolysis. Reaction of the disulphonate 5 with methanolic sodium methoxide afforded 1- D -1,2:5,7-dianhydro-5- C -hydroxymethylcyclohexane-1,2,3,5/0-tetrol ( 6 ). The ring-opening reactions of the diepoxide 6 with azide ion furnished a mixture of two diazides 9 and 13 in the ratio 4 to 1. The structure and conformation of the derived dibenzoates 10 and 14 have been determined by n.m.r. spectroscopy.

Synthesis of trans-(3S,4S)-dibenzyloxycyclopentanone

The 1-cyano-1-thiophenylcyclopentone derivative 1, obtained from (R,R)-(+)-tartaric acid, has been converted into a number of derivatives including the important trans-(3S,4S)-dibenzyloxycyclopentanone 2 in 45% overall yield.

Novel (4 + 1) fragment combination approach to chiral cyclopentanoids from tartaric acid

A chiral cyclopentanoid building block 29 has been synthesized in “one pot” cyclization process from epoxides 22 - 25 (which are readily accessible from (R,R)-(+) tartaric acid) with the carbanion derived from phenylthioacetonitrile (PhS-CH2-CN).

Synthesis of aminocyclitols from l-quinic acid

Abstract A variety of 1,3-diamino and 1,4-diaminocyclitols, manoaminocyclitols, and triaminocyclohexanol have been synthesized starting with the chiral ketone intermediate, 2, derived from l -quinic acid. Reduction of 2 with lithium borohydride afforded two epimeric diols (4 and 5), both of which were transformed by straight-forward but distinctly different chemical procedures into potentially useful aglycons for preparing novel tupes of bioactive, aminocyclitol glycoside antibiotics. The disposition of the substituents at C-1, C-3, C-4, and C-5 in 19 and 37 is identical with that present in the 2-deoxystreptamine nucleus in the naturally occurring antibiotics

Synthesis of 3α-alkoxy-4β-substituted-2-azetidinones from L(+)-tartaric acid.

Abstract Tartaric acid, regioselective saponification, Pig Liver Esterase, 3-methoxy-2-azetidinone, N -Hydroxy-2-thiopyridone, radical decarboxylation. The synthesis of 3α-alkoxy-4β-azetidinones from L(+) tartaric acid is described. Regioselective saponification and methylation along with a stereo selective radical decarboxylative alkylation are key steps leading to optically pure trans-β-lactams.

Synthesis of α-linked 3′-deoxy-cyclitol and -aminocyclitol glycosides

Unsaturated and saturated α-linked cyclitol and aminocyclitol glycosides have been prepared by a boron trifluoride–ether catalysed addition reaction of (3) and (4) to the appropriately functionalised cyclitol derivatives (2), followed by regiospecific hydrogenation from the β face; the structure and conformation of all products have been proved by 1H and 13C n.m.r. spectroscopy and chemical ionisation mass spectrometry.

Synthesis of α-linked 3′-deoxy-pseudo-di- and -tri-saccharides related to aminocyclitol-glycoside antibiotics

The syntheses of the title compounds, precursors of all types of modified aminocyclitol glycoside antibiotics substituted at position 4 or positions 4 and 5 of the aminocyclitol aglycone, are reported.

Synthesis of ethyl 2,6-diacetamido-2,3,6-trideoxy-α-D-ribo-hexopyranoside, a derivative of the diamino-sugar component of the antibiotic nebramycin factor 6

Derivatives of a new diaminotrideoxy-D-hexose, a carbohydrate component of the pseudotrisaccharide antibiotic nebramycin factor 6 have been prepared; the synthesis is based on a conjugate 1,4-addition of azide ion on the α,β-unsaturated ketone (2).

Synthesis of derivatives of sisosamine and purpurosamine C: confirmation of the structure of sisomicin

The synthesis of derivatives of sisosamine (12) and purpurosamine C (16), components of the amino-glycoside antibiotics, sisomicin (1) and gentamicin C1a(2) is described; one key intermediate, 2-azido-2,3-dideoxy-6-O-toluene-p-sulphonyl-α-D-erythro-hexopyranosid-4-ulose (5) being used for both reaction sequences.