Juji Yoshimura

Stereoselective and Efficient Total Synthesis of Optically Active Tetrodotoxin from d-Glucose

A stereoselective and efficient total synthesis of optically active tetrodotoxin (TTX) is described. A polyfunctionalized key cyclitol compound containing branched-chains for the synthesis of TTX was prepared from D-glucose employing the Henry reaction (Nitro aldol reaction) as the key transformation. Stereoselective construction of the alpha-azido-aldehyde branched-chain was achieved via the key spiro alpha-chloroepoxide intermediate.

The synthesis of evernitrose and 3-epi-evernitrose☆

Abstract Evernitrose (2,3,6-trideoxy-3- C -methyl-4- O -methyl-3-nitro- L - arabino -hexopyranose) was synthesized from methyl 2,6-dideoxy-4- O -methyl-α- L -erythro-hexopyranosid-3-ulose ( 2 ) through introduction of an amino group attached to the tertiary branching carbon by the method of Bourgeois, and subsequent oxidation of the amino group by m -chloroperoxybenzoic acid to a nitro group. 3-Cyano-3- O -mesylation of 2 by Bourgeoiss method gave exclusively the desired product having the L - ribo configuration; furthermore, the β anomer of 2 gave the L - ribo and L - arabino products in the ratio of 1:2. The latter compound was converted into 3- epi -evernitrose by a similar sequence of reactions.

Branched-chain sugars : VII. Determination of the configuration of L-vinelose by synthesis

Abstract The configuration of L-vinelose was unequivocally determined to be 6-deoxy-3-C-methyl-2-O-methyl- l -talose by comparing an authentic specimen with the synthetic product obtained in eleven steps from 1,2:5,6-di-O-isopropylidene-3-C-methyl-α- d -allofuranose.

Synthesis of destomic and epi-destomic acid, and their C-6 epimers

Four stereoisomers of 6-amino-6-deoxyheptonic acid, having the l-glycero-d-galacto (1), d-glycero-d-galacto (2), l-glycero-d-gluco (3), and d-glycero-d-gluco (4) configurations, were synthesized from d-galacto- (8) and d-gluco-dialdose (23) derivatives, respectively. Cyanomesylation of 8 and 23 gave two C-6 epimers, respectively, which were separately converted, via the corresponding 6,7-epimino derivatives, into 6-(benzyloxycarbonyl)amino-6-deoxy derivatives by reduction with lithium aluminum hydride, N-(benzyloxycarbonyl)ation, and acetolysis with acetic acid. After deprotection of each hemiacetal, the stereoisomers were oxidized with bromine, followed by total deprotection, to give 1–4. Among these products, 1 and 3 proved to be identical with the naturally occurring destomic and epi-destomic acid obtained from antibiotic destomycins.

A new synthesis of 2,3,4,6-tetra-O-benzyl-D-glucopyranosylidene acetals, using trimethylsilyl trifluoromethanesulfonate as the catalyst

Abstract The title compounds were synthesized by condensation of 2,3,4,6-tetra- O -benzyl- d -glucono-1,5-lactone with bis- O -(trimethylsilyl)-1,2-diols in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst. Application to cis - and trans -1,2-diols containing primary, secondary, and tertiary hydroxyl groups was examined, and a new rearrangement was found in the reaction of a d -glucono-1,5-lactone derivative having an acetyl group at O-6.

Stereoselectivities in the reaction of methyl 4,6-O-benzylidene-α- and -β-d-hexopyranosid-2-uloses with diazomethane

Abstract The stereoselectivities in the reaction with diazomethane of methyl 4,6-O benzylidene-3-O-methyl-α- d -arabino-hexopyranosid-2-ulose (2), its 3-epimer (3), its β anomer (5), and the corresponding 3-O-benzoyl derivative (4) have been examined in comparison with those in the Grignard reaction and in reduction with sodium borohydride. The opposite stereoselectivity of the diazomethane reaction, with equatorial attack on α anomers (2 and 3) and axial attack on β anomers (4 and 5), to that of the other reactions, is explained by an attractive, electrostatic interaction in the transition state between the diazomethyl cation and either the axial O-1 of the methoxyl group or lone-pair electrons of O-5.

The synthesis of fragment A of an antibiotic, nosiheptide

Abstract Fragment A derivative (13) of nosiheptide, useful for the total synthesis, was obtained by stepwise introduction of the 2,5-bis{(4-ethoxycarbonyl)-2-thiazolyl} groups and 6-{(2-substituted)-4-thiazolyl} group into 3-hydroxy-5-cyanopyridine(3). The total yield was 7.6% via 14 steps.

New syntheses of methyl 4,6-O-benzylidene-2-deoxy-3-C-methyl-α-d-arabino-hexopyranoside and its conversion into d-evermicose

Abstract Methyl 4,6- O -benzylidene-2-deoxy-3- C -methyl-α- d - arabino -hexopyranoside ( 4 ) was prepared from methyl 4,6- O -benzylidene-2,3-dideoxy-3- C -methylene-α- d -erythro-hexopyranoside ( 1b ) and from methyl 4,6- O -benzylidetic-3 C -methyl-α- d - gluco -hexopyranoside ( 6a ) by two different methods. Synthesis of d -evermicose‡ ( 10 (2,6-dideoxy-3- C -methyl- d -arabino-hexose) was then achieved in four steps from 4 .

Facile syntheses of 3-spiro- and 3,6-bridged 2,5-piperazinediones

Abstract The intramolecular addition of hydroxyl group of 3-(3-hydroxyl)propylidene-2,5-piperazinedione to 3-position and the same substitution of 3-(3-hydroxy)propyl derivative to 6-position gave the corresponding 3-spiro- and 3,6-bridged 2,5-piperazinediones, respectively.

Synthesis of methyl 2,3-O-glycopyranosylidene-α-d-mannopyranosides having various substituents

Abstract The title compounds were obtained by condensation of d -glucono-, d -galactono-, or l - glycero - d - gluco -heptono-1,5-lactones with methyl 2,3-di- O -(trimethylsilyl)-α- d -mannopyranosides having various substituents on C-4 and C-6, in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst. Except for a 6-acetoxyl group on a lactone component and a ( tert -butyldiphenylsiloxy) group, the usual C -substituents, such as benzyloxy, allyloxy, azido, acyloxy, (methylthio)methoxy, and methoxy, did not prevent occurrence of this condensation.