Ryo Yazaki

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Alcohol withdrawal symptoms in 19 male alcoholics were objectively evaluated and classified and circadian variation in their plasma 5-hydroxyindoleacetic acid (5-HIAA) concentrations was determined at 3 different intervals after cessation of drinking. Circadian variations in plasma 5-HIAA level exhibited phase advances in alcoholic patients compared with(More)
The total synthesis of onchidin (1), a cytotoxic, C2-symmetric cyclic decadepsipeptide from a marine mollusc, according to the published structure, is described. A novel beta-amino acid, (2S,3S)-3-amino-2-methyl-7-octynoic acid (AMO), was efficiently prepared in high yield with high diastereo- and enantioselectivity based on a catalytic asymmetric(More)
A detailed study of the direct catalytic asymmetric conjugate addition of terminal alkynes to α,β-unsaturated thioamides is described. A soft Lewis acid/hard Brønsted base cooperative catalyst, comprising [Cu(CH(3)CN)(4)]PF(6), bisphosphine ligand, and Li(OC(6)H(4)-p-OMe) simultaneously activated both substrates to compensate for the low reactivity of(More)
Alcohol withdrawal symptoms in alcoholics were objectively evaluated and classified into three groups according to the severity of their symptoms, and circadian variation in their plasma homovanillic acid (HVA) concentrations was determined at three different intervals after cessation of drinking. The subjects studied were 19 male alcoholic patients and(More)
A concise enantioselective synthetic route to a potent GPR40 agonist AMG 837 is described. The crucial catalytic asymmetric conjugate addition of terminal alkyne was promoted by a soft Lewis acid/hard Brønsted base cooperative catalyst, allowing efficient construction of the requisite stereogenic center. The thioamide functional group is key to both(More)
A direct catalytic asymmetric addition of allyl cyanide to ketones with a bimetallic catalytic system comprising (R,R)-Ph-BPE/[Cu(CH(3)CN)(4)]ClO(4)/LiOAr is described. Exclusive gamma-addition of allyl cyanide was observed, affording optically enriched tertiary alcohols bearing Z-configured alpha,beta-unsaturated nitriles. The reaction proceeded under(More)
We report that a hard Lewis base substantially affects the reaction efficiency of direct catalytic asymmetric gamma-addition of allyl cyanide (1a) to ketones promoted by a soft Lewis acid/hard Brønsted base catalyst. Mechanistic studies have revealed that Cu/(R,R)-Ph-BPE and Li(OC(6)H(4)-p-OMe) serve as a soft Lewis acid and a hard Brønsted base,(More)
A highly chemoselective conjugate addition of alcohols in the presence of amines is described. The cooperative nature of the catalyst enabled chemoselective activation of alcohols over amines, allowing the conjugate addition to soft Lewis basic α,β-unsaturated nitriles. Divergent transformation of the nitrile functionality highlights the utility of the(More)
Catalytic asymmetric conjugate addition of nitroalkanes to α,β-unsaturated thioamides is promoted by a mesitylcopper/(R)-DTBM-Segphos precatalyst, affording γ-nitrothioamides in moderate to high syn-selectivity and excellent enantioselectivity. The intermediate Cu-thioamide enolate functions as a soft Lewis acid/hard Brønsted base cooperative catalyst to(More)
Direct catalytic asymmetric addition of allylic cyanides to N-diphenylphosphinoyl ketoimines with a bimetallic catalytic system comprising Ph-BPE/[Cu(CH3CN)4]ClO4/LiOAr is described. Intermediary alpha-adducts readily isomerized to afford synthetically useful alpha,beta-unsaturated nitriles bearing an optically active tetrasubstituted carbon. Applicability(More)