Kin-ichi Tadano

Stereoselective synthesis of the bis(tetrahydrofuran) moiety (C-1 to C-9) of (+)-asteltoxin, a novel mycotoxin from aspergillus stellatus

Abstract The bis(tetrahydrofuran) moiety of (+)-asteltoxin which possesses six asymmetric carbons has been synthesized stereoselectively. The synthesis was started from a highly functionalized tetrahydrofuran prepared from D-glucose.

An Alternative Synthesis of Acosamine and Ristosamine

Abstract The Henry reaction of (2S)-2-benzyloxypropanal with (2S)-1,2-O-isopropylidene-4-nitro-1,2-butanediol, leading to naturally occurring 3-amino-2,3,6-trideoxy-L-hexoses, acosamine and ristosamine, is described.

Total synthesis of (−)-swainsonine, an α-d-mannosidase inhibitor isolated from Swainsona canescens

Abstract A newly isolated alkaloidal toxin, (−)-swainsonine [(1 S ,2 R ,8 R ,8a R )-1,2,8-trihydroxyoctahydroindolizine], which exhibits an α- d -mannosidase inhibitory activity, has been synthesised stereoselectively in 15 steps starting from methyl 3-acetamido-2,4,6-tri- O -acetyl-3-deoxy-α- d -mannopyranoside.

Total synthesis of (-)-mniopetal E, a novel biologically intriguing drimane sesquiterpenoid

We have achieved the total synthesis of (−)-mniopetal E, a drimane sesquiterpenoid which inhibits the reverse transcriptase of human immunodeficiency virus (HIV)-1. Our enantiospecific total synthesis of this target molecule in naturally occurring form commenced with a known 2,3-anhydro-d-arabinitol derivative, which was prepared using the Sharpless asymmetric epoxidation strategy. The key steps of our total synthesis were as follows:  (1) a combination of highly stereocontrolled inter- and intramolecular Horner−Emmons carbon elongations for construction of a butenolide tethering a 1,2,4,9-functionalized nona-5,7-diene moiety at the β-carbon, (2) stereoselective thermal intramolecular Diels−Alder reaction of the thus-formed trienic compound, providing preferentially an endo-cycloadduct with the desired π-facial selection, and (3) efficient transformation of the γ-lactone moiety in the major cycloadduct to the γ-hydroxy-γ-lactone part in mniopetal E. Our total synthesis of (−)-mniopetal E established the u...

Total synthesis of PI-091

Abstract Total synthesis of PI-091 (1), a novel platelet aggregation inhibitor, has been accomplished. The known D-glucose-derived branched sugar 2 was converted efficiently to a 2,4-disubstituted furan 4. The total synthesis of 1 was completed featuring a singlet oxygen addition to 4 and a lactone-lactam transformation of 3.

Total synthesis of (+)-asteltoxin1

Abstract A total synthesis of (+)-aste1toxin, a novel mycotoxin isolated from Aspergillus stellatus, has been achieved by using D-glucose as an enantiomerically pure starting material.

Total synthesis of (−)-acetomycin

Abstract Enantiospecific total synthesis of the rifled antibiotic ( 1 ) has been completed. The pentasubstituted tetrahydrofuran ( 3 ), efficiently obtained from D-glucose, was used as an enantiomerically pure starting material.

A Chiral Synthesis of (+)-Pseudoconhydrine

Abstract (+)-Pseudoconhydrine, one of hemlock alkaloids, has been synthesized from methyl 2-acetamido-2,3,4-trideoxy-α-D-erythro-hexopyranoside by an eleven step reaction sequence. An intramolecular nucleophilic attack of the nitrogen atom on 2-acetamido-5-0-benzyl-2,3,4-trideoxy-6-0-tosyl-D-reythro-hexose diethyl di-thioacetal to the terminal tosyloxymethylene group proceeded smoothly and gave the desired disubstituted piperidine compound. A conversion of the thioacetal group into an aldehyde, a two-carbon elongation by Wittig olefination, and a successive hydro-genation completed the chiral synthesis of the title alkaloid.

Synthetic studies on the trichothecene family from D-glucose

Abstract Base-catalyzed intramolecular cyclizauon of D-glucose-derived substrate 10 provided a diastereomeric mixture of bicyclic β-hydroxyl diesters 6 R and 6 S . Further functionalization of the mixture afforded an enantiomerically pure bicyclic lactone 4 . A double alkylation of 4 provided 3 stereoselectively. Dieckmann cyclization of a lactone-ester 2 , which was prepared from 3 , followed by protection of a hemiacetal hydroxyl group provided smoothly a tricyclic compound 1 .

An alternative synthesis of (1R,2S,3R,4R)-2,3-dihydroxy-4-hydroxymethyl-1-cyclopentanamine, a synthetic intermediate of (−)-aristeromycin

Abstract The title compound, an enantiomerically pure carbocyclic portion of the antibiotic (−)-aristeromycin, has been synthesized from D-erythrose. The synthesis involves a transformation of the known carbocyclic analogue of β- L -arabinofuranose to the α- D -ribo form by silica gel promoted epimerization at the branched carbon.