Yoshihiro Yokokawa

Total syntheses of myriocin and Z-myriocin, two potent immunosuppressants, from 2-deoxy-d-glucose☆

Abstract Total syntheses of myriocin (thermozymocidin, ISP-1, 21) and its analog, Z-myriocin (22), which showed potent immunosuppressive activity, were accomplished starting from 2-deoxy- d -glucose by employing a modified Darzen reaction as a key reaction. The stereoselectivity of the modified Darzen reaction for six-membered cyclic ketones was discussed on the basis of physicochemical evidence including the conformational analyses of the cyclic ketones based on molecular mechanics calculation.

Stereoselective conversion of D-glucuronolactone into pseudo-sugar: Syntheses of pseudo -α-D-glucopyranose, pseudo-β-D-glucopyranose, and validamine

Abstract Two optically active pseudo -sugar, pseudo -α- D -glucopyranose ( 12 ) and pseudo -β - D -glucopyranose ( 13 ), were synthesized from D -glucuronolactone in favorable overall yields by using a stereoselective nitromethane addition reaction and a reductive elimination of an ethoxyethoxyl moiety with NaBH 4 as key steps. Furthermore, a biologically active pseudo -aminosugar, validamine ( 18 ) was efficiently synthesized via a substitution reaction for an acetoxyl group at the β-position of nitro group in a nitrocyclitol derivative ( 14 ) which was prepared from a synthetic intermediate ( 9 ) of pseudo - D -glucopyranoses ( 12, 13 ).

Facile syntheses of pseudo-α-d-arabinofuranose, and two pseudo-d-arabinofuranosylnucleosides, (+)-cyclaradine and (+)-1-pseudo-β-d-arabinofuranosyluracil, from d-arabinose

Abstract An optically active pseudo-sugar, pseudo-α- d -arabinofuranose, was efficiently synthesized from d -arabinose by using a stereoselective nitromethane addition reaction to form a branched nitropyranose (6) as a key step. Furthermore, two biologically active pseudo-β- d -arabinofuranosylnucleosides, (+)-cyclaradine and (+)-1-pseudo-β- d -arabinofuranosyluracil, were also synthesized from the nitrocyclopentene derivative (12), which was prepared from a synthetic intermediate of pseudo-arabinofuranose, via Michael-type reaction introducing nucleic acid base moieties.