Ken Ohmori

Synthetic studies on bryostatins, antineoplastic metabolites: Convergent synthesis of the C1-C16 fragment shared by all of the bryostatin family

Abstract The C1-C16 fragment of bryostatins could successfully be synthesized by tandem connection of the appropriate three fragments and effective introduction of the α,β-unsaturated esters at the C13 position.

CHEMICAL STUDY ON HAPALOSIN, A CYCLIC DEPSIPEPTIDE POSSESSING MULTIDRUG RESISTANCE REVERSING ACTIVITIES : SYNTHESIS, STRUCTURE AND BIOLOGICAL ACTIVITY

Abstract Hapalosin 1 possessing a multidrug resistance reversing activity, has been synthesized from the corresponding hydroxy acids A, C and γ-amino acid B . The stereochemistry of the natural product 1 and N-demethylhapalosin 11 is discussed by means of spectroscopic manner as well as molecular modeling studies. Biological evaluation of 1 and 11 indicated that a cis-amide function is a crucial factor for the MDR reversing activity.

Synthetic study on hapalosin, a cyclic depsipeptide possessing multidrug resistance reversing activities

Abstract Hapalosin possessing a multidrug resistance reversing activity, has been synthesized from the corresponding hydroxy acids and γ-amino acids. The stereochemistry of the natural product and related derivatives is discussed.

(-)-(3S)-4-(2-{[4,4-Dimethoxy-6-(benzyloxymethyl)perhydropyran-2-yl]methyl}-1,3-dithian-2-yl)-4-methyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)pentan-1-ol.

The absolute configuration was determined for the title compound, (-)-C(32)H(56)O(6)S(2)Si, (I), which was prepared in a synthetic study on the natural products bryostatins. Two independent molecules show similar conformations, except for the orientation of the methoxy groups.

(+)-3-{(4S,5S)-5-[1,1-dimethyl-2-(phenylthio)ethyl]-2,2-dimethyl-1,3-dioxolan-4-yl}prop-2-yn-1-ol

The absolute configuration was determined for the title compound, (+)-C(18)H(24)O(3)S, (I), which was prepared in a synthetic study on the natural products, bryostatins.