Asymmetric induction bny enantiotopically differentiatingretro-claisen reaction of P{rochiral bicyclic ?-diketones
作者:Rudolf O. Duthaler、Peter Maienfisch
DOI:10.1002/hlca.19840670325
日期:1984.5.2
possibility of preparing cycloalkanones with an asymmetric β-C-atom by enantiotopically differentiating retro-Claisen reactions of bicyclic diketones a (Scheme l) is tested with the decalin-1,8-diones 1 and 7, as well as with the bicyclo[3.3.0]octane-2,8-diones 10 and 11. Treatment of the reactive dione 1 with chiral tetra-alkyl titanate catalysts results in a low optical induction (13%, Scheme 2). Cleavage
Preparation of Bicyclo[3.3.0]octane-2,8-dione- and Declain-1,8-dione-Derivatives
作者:Rudolf O. Duthaler、Peter Maienfisch
DOI:10.1002/hlca.19840670326
日期:1984.5.2
Alkylation of bicyclo[3.3.0]octane-2,8-dione (1), which is prepared by a modification of the procedure described in the literature, gives the methyl- and propynyl-derivatives 6 and 7 (Scheme 1). In addition to the method described previously (Scheme 2), 9-methyl-cis-decalin-1,8-dione 9 is obtainable stereoselectively either by cyclization of keto-acid 16, or by aldol cyclization of keto-aldehyde 26
Synthesis of optically pure compounds by enantiotopically differentiating monoacetalization of prochiral diketones
作者:Rudolf O. Duthaler、Peter Maienfisch
DOI:10.1002/hlca.19820650303
日期:1982.5.5
(2) and of its trans-isomer (3) with (2R,3 R)-2,3-butanediol (8) gives in both cases the monoacetals in high yield. While no enantiotopicdifferentiation is found for 3, a strong preference for the (9S,10 R)-monoacetal 9 is found for the cis-decalin-dione 2. The differentiation, reaching a maximal ratio of 9:1, is found to increase by conditions, which slow down the rate of reaction, e. g. lowering the