|Budget Amount *help
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
The following subjects were explored for verification of the effectiveness of hexofuranoses and hexopyranoses as stereocontroller for diastereoselective carbon-carbon bond forming reactions.
1. The orthoester Claisen rearrangement of (Z)-3-deoxy-3-C-[(hydroxymethyl)methylene]-1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofuranose with 1,1-dimethoxycyclohexane provided a 3.3:1 diasteromeric mixture of the rearrangement products. The Claisen rearrangement with 3,3-dimethoxycyclohexene provided a single product. Hydride additions and 1,4-conjugate additions for these rearrangement products were investigated, and some of the additions proceeded highly stereoselectively.
2. The conjugate additions of a variety of organocopper reagents or dimethyl malonate anion to a spirocyclic cyclopent-2-enone connecting a 1,2:5,6-di-O-isopropylidene-α-D-glucofuranosyl ring as a constituent of the spirocyclic structure proceeded stereoselectively affording a variety of β-functionalized cyclopentanone derivatives
. In addition, the thermal treatment of (1S,3R,4R,5S)-7-(hydroxymethyl)-3,4-(isopropylidenedioxy)1-[(1R)-1.2-(isopropylidenedioxy)ethyl]-2-oxaspiro[4.4]non-6-ene with triethyl orthoacetate afforded the Claisen rearrangement product with a high level of diastereoselectivity.
3. The 1,4-conjugate additions of a variety of organocopper reagents to some 4-O-crotonyl derivatives of methyl α-D-glucopyranoside proceeded with exceptionally high levels of diastereochemical induction to provide the adducts carrying a β-vinylated (or alkylated) butanoic ester at the C-4 carbon atom. The 1,4-conjugate additions to a 6-O-crotonyl derivative aforded the adduct incorporating reverse configuration at the β-carbon to that obtained from the 4-O-crotonyl derivatives. Removal of the carbohydrate template from each adduct provided β-vinylated (or alkylated) butanoic acid in enantiopure or highly-enriched form. The conjugate addition of alkyl radicals to the above mentioned 4-O-crotonyl derivative proceeded with high stereoselectivity. The D-galactose-derived and D-mannose-derived 2-O-, 3-O-crotonyl esters also served as good stereocontrollers for 1,4-conjugate addition reactions and Diels-Alder reactions. Less