Hiroto Nagaoka

Enantioselective synthesis of (R)- and (S)-4-[(methoxycarbonyl)-methyl]-2-azetidinones from D-glyceraldehyde acetonide

Abstract (R)-N-Benzyl-4-[(methoxycarbonyl)methyl]-2-azetidinone ( 10 ) and (S)-4-[(methylcarbonyl)methyl]-2-azetidinone ( 17 ) were enantioselectively synthesized from the benzylamino ester 3 , which was prepared by the highly stereoselective 1,4-addition of benzylamine to the α,β-unsaturated ester 2 derived from D-glyceraldehyde acetonide ( 1 ).

Total synthesis of marine prostanoids clavulones

Abstract An enantioselective and stereoselective synthesis of novel marine prostanoids clavulone II (1) and 12-O-desacetylclavulone II (2) has been accomplished.

Aragusterol a: A potent antitumor marine steroid from the okinawan sponge of the genus, Xestospongia

Abstract Aragusterol A, a new marine steroid possessing potent antitumor activity, was isolated from the Okinawan sponge of the genus Xestospongia and its structure was determined by spectroscopic analysis and chemical evidence. The compound strongly inhibited the cell proliferation of KB, HeLaS3, P388 and LoVo cells in vitro , and also showed potent in vivo antitumor activity toward P388 in mice and L1210 in mice.

Determination of absolute configuration of chlorovulones by cd measurement and by enantioselective synthesis of (−)-chlorovulone II1

Abstract Absolute configuration of chlorovulones, new halogenated marine prostanoids with an antitumor activity isolated from the stolonifer Clavularia viridis Quoy and Gaimard, has been established on the basis of the CD measurement of the chlorovulone derivatives and of the enantioselective synthesis of (−)-chlorovulone II.

Total synthesis of upial

Abstract Highly stereocontrolled synthesis of marine sesquiterpene upial was achieved from D -mannitol via fragmentation reaction of tricyclic compound 10 and samarium(II) iodide-induced cyclization of diformate 2.

Total synthesis of marine diterpene fuscol

Abstract Marine diterpene fuscol was synthesized stereoselectively from D-mannitol via bicyclo[2.2.2]octane derivative 4. and its complete structure was established.

A new synthetic approach to the bicyclo[5.3.1]undecane ring system in taxanes

Abstract The bicyclo[5.3.1]undecane derivative 19, which was referred to the A,b ring system of taxane diterpenes, was synthesized by a base-induced fragmentation reaction of the tricyclic diol monomesylate 18 derived highly stereoselectively from 5-methyl-1,3-cyclohexadione.

Total synthesis of (±)-sanadaol

Abstract The first total synthesis of (±)-sanadaol, a structurally unique marine diterpene, was achieved in a fully stereocontrolled manner.

Total synthesis of (±)-gibberellic acid

Abstract Total synthesis of (±)-gibberellic acid was accomplished via highly stereocontrolled route.

Samarium(II) iodide-induced tandem reductive coupling-Dieckmann condensation reaction: one-step synthesis of bicyclic oxacyclopentanecarboxylate from bis-α,β-unsaturated esters

Abstract The tandem cyclization of bis-α,β-unsaturated esters with SmI 2 -Sm–THF in the presence of catalytic amount of methanol was found to stereoselectively provide bicyclo[4.3.0]nonan-8-ones and bicyclo[3.3.0]octan-3-ones.