Masanori Hatsuda

Effects of torsional angles of 2,2′-biaryldiol ligands in asymmetric Diels-Alder reactions of acrylates catalyzed by their titanium complexes

Abstract In the asymmetric Diels-Alder reaction of acrylates with cyclopentadiene catalyzed by a series of chiral titanium complexes derived from 2,2′-biaryldiols 1–3 , ees of the endo -adducts depend on the torsional angles of the ligands and are maximal when 1,1′-bi-2-naphthol 1 or 6,6′-hexylenedioxy-2,2′-biphenyldiol 2e is used.

Facile synthesis of enantiopure 1,1′-binaphthyl-2,2′-dicarboxylic acid via lipase-catalyzed kinetic resolution

Abstract Enantiopure 1,1′-binaphthyl-2,2′-dicarboxylic acids (R)-1 and (S)-1 have been synthesized through the lipase-catalyzed kinetic resolution of the racemic 2,2-bis(hydroxymethyl)-1,1′-binaphthyl (±)-2 and subsequent oxidation of the hydroxymethyl groups.

An Improved Synthesis of ( E )-Cinnamic Acid Derivatives via the Claisen–Schmidt Condensation

Abstract A variety of (E)-cinnamic acid derivatives are prepared in high yields through the Claisen–Schmidt condensation in the presence of sodium metal and a catalytic amount of methanol with toluene employed as the co-solvent.

A highly stereocontrolled total synthesis of (+)-biotin from l-cysteine

Abstract (+)-Biotin was synthesized in 11 steps and in 25% overall yield from readily accessible l -cysteine through a Lewis base-catalyzed highly diastereoselective cyanosilylation of (2R,4R)-N-Boc-2-phenylthiazolidine-4-carbaldehyde 2 and a ring closure of a cis-allylic carbonate 5b utilizing a palladium-catalyzed intramolecular allylic amination.

Facile synthesis of C2-symmetric chiral binaphthyl ketone catalysts

Abstract C2-Symmetric chiral binaphthyl ketones, efficient catalysts for asymmetric epoxidation, have been synthesized through an intramolecuar Ullmann reaction and/or a lipase-catalyzed enantioselective hydrolysis of the 11-membered cyclic binaphthyl acetate.

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.