Shin-ichi Yoshida

Synthetic study on aplysiatoxins, highly inflammatory agents and tumor promoters synthesis of the three optically active segments

Abstract The main segments in debromoaplysiatoxin and related aplysiatoxins have been efficiently synthesized from D-glucose and L- and D-tartaric acids.

A new stereocontrolled synthesis of diequatorial furofuran lignans having two different aryl groups : a synthesis of methyl piperitol

Abstract Methyl piperitol, a representative example of the diequatorial furofuran lignans, was synthesized in a good overall yield based on a highly stereocontrolled tandem Michael addition-aldol reaction.

Asymmetric syntheses of lignans utilizing novel diastereoselective Michael addition of cyanohydrin: Syntheses of (+)-fargesin and (−)-picropodophyllone

Abstract The Michael addition reaction of lithium salt of cyanohydrin to (S)- and (R)-3-(2,2-dimethyl-1,3-dioxolan-4-yl)-cis-2-propenoate (2 and 3) proceeded in 93% de in the presence of two equivalents of HMPA at −100 °C. This diastereoselectivity could be elucidated by the stereocontrol based on the 1,3-allylic strain. Utilizing this reaction, stereocontrolled syntheses of (+)-fargesin (6) and (−)-picropodophyllone (7) were achieved.

A new stereocontrolled synthesis of axial-equatorial furofuran lignans having two different aryl groups: A synthesis of Fargesin

Abstract Fargesin, a representative example of the axial-equatorial furofuran lignans, was synthesized in a good overall yield based on a new method for inversion of the stereochemistry at C-4 of 1 .

Synthetic study on breynin A : Synthesis of breynolide sulfone

Abstract In connection with breynin A having a significant hypocholesterolemic activity in rats, an optically active perhydrobenzothiophene has been synthesized starting from L-carvone in 11% overall yield. Furthermore, this sulfur-containing bicyclic segment has been successfully converted into an oxygenated breynolide.

A NOVEL ASYMMETRIC SYNTHESIS OF AXIAL-EQUATORIAL FUROFURAN LIGNANS : A SYNTHESIS OF (+)-FARGESIN

Abstract (+)-Fargesin (6), a representative example of the axial-equatorial furofuran lignans having two different aryl groups, was efficiently synthesized based on a highly diastereoselective Michael addition reaction of the cyanohydrin 1 to methyl (S)-3-(2,2-dimethyl-1,3-dioxolan-4-yl)-cis-2-propenoate (2).

The first synthesis of diaxial bislactone furofuran lignan

Abstract The diaxial bislactone furofuran lignan 6 was first synthesized on the basis of a stereocontrolled aldol reaction of the acid anhydride 1 and veratraldehyde.

The first stereocontrolled synthesis of axial-equatorial bislactone furofuran lignans having two different aryl groups: A synthesis of methyl 4, 8-dioxoxanthoxylol

Abstract Methyl 4, 8-dioxoxanthoxylol (1), a representative example of the axial-equatorial bislactone furofuran lignans having two different aryl groups, was synthesized based on the stereocontrolled aldol reaction of the acid anhyderide3 and veratral.

A Practical Synthesis of (+)-Biotin from L-Cysteine

Alpha-amino aldehyde 4, which is readily derived from L-cysteine through cyclization and elaboration of the carboxy group, was subjected to the Strecker reaction, which, via sodium bisulfite adduct 16, afforded alpha-amino nitrile 5 with high diastereoselectivity (syn/anti=11:1) and in high yield. Amide 6, derived from 5, was converted to thiolactone 8, a key intermediate in the synthesis of (+)-biotin (1), by a novel S,N-carbonyl migration and cyclization reaction. The Fukuyama coupling reaction of 8 with the zinc reagent 21, which has an ester group, in the presence of a heterogeneous Pd/C catalyst allowed the efficient installation of the 4-carboxybutyl chain to provide 9. Compound 9 was hydrogenated and the protecting groups removed to furnish 1 in 10 steps and in 34 % overall yield from L-cysteine.