|Budget Amount *help
¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1990 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1989 : ¥1,300,000 (Direct Cost : ¥1,300,000)
1. The ortho-ester Claisen rearrangement (Johnson-Claisen rearrangement) is one of the highly stereoselective carbon-carbon bond forming reaction in current organic synthesis. Our interest is a pursuit of the highly stereoselective Claisen rearrangement reaction applied to carbohydrate-derived substrates for access to versatile chirons. The ortho ester Claisen rearrangement of Z-isomer of 3, 5, 6-trideoxy- 1, 2-OMICRON-isopropylidene-3-C-methyl-alphaーD-ribo-hept-5-eno-1, 4-furanose with triethyl orthoacetate proceeded highly stereoselectively to form the major rearrangement product with (S)- newly introduced asymmetric center (9 to 1 diastereoselectivity). This product includes a 1, 3-dimethylー2, 4-diol substructure, and is expected to be a useful building block for such the macrolide synthesis (J. Carbohydrate Chem., in press).
2. The utility of the rearrangement product has been embodied through total synthesis of natural products such as (+)-asteltoxin. The subject of this Grantーinーaid is the total synthesis of (-)-acetomycin, an antimicrobial and antitumor agent. The starting material for the total synthesis was the major product obtained by the Claisen rearrangement of D-glucose derived allylic alcohol at C-3 and triethyl orthopropionate. This first total synthesis of (-)-acetomycin established its absolute configuration. In the course of the total synthesis, one of the stereocongeners of the antibiotic, (+)-5-epiーacetomycin was also synthesized. From the minor product of the Claisen rearrangement, the other two stereocongeners, 4-epi-, and 4, 5-di-epi-acetomycin were synthesized by analogous reaction sequence adopted to the (-)-acetomycin synthesis.