Abstract
The studies on the application of chiral 1,3-dioxolan-4-ones, derived from (1S)-(+)-N,N-diisopropyl-10-camphorsulfonamide 25, in asymmetric synthesis are described. This thesis consists of three parts. The first and second parts are concerned with applications of chiral 1,3-dioxolan-4-ones 48, 50 and 51 in asymmetric aldol and 1,4-addition reactions to synthesize optically active compounds. In the third part, an enantioselective formal synthesis of (+)-k252a is described. 1) Asymmetric aldol reaction: Aldol reactions of the enolates of 1,3-dioxolan-4-one 50 and 51 with various aldehydes afforded corresponding products 61, 62, 63 and 64 in 74-91% yield. The reactions of 1,3-dioxolan-4-one 50 with isobutyaldehyde or 1,2-dihydrocinnamaldehyde and of 1,3-dioxolan-4-one 51 with isobutyaldehyde afforded single product 63b, 63e and 63h. The diastereoselective ratio of the reaction of 1,3-dioxolan-4-one 51 with 1,2-dihydrocinnamaldehyde is 14 : 1. The diastereoselective ratios of the other cases are in 1 : 2 to 1 : 8. On the other hand, all of the reactions of 1,3-dioxolan-4-one 51 with various aromatic aldehydes afforded single products 62f-k as a single stereoisomer. 2) Asymmetric 1,4-addition reaction: The addition of 1,3-dioxolan-4-ones 48 and 50 to □,□-unsaturated esters afforded single product in 77%~92% yield. Subsequent hydrolysis of these adducts 67b-e and 68g give (+)-trans-crobarbatic acid 72 and 3,4-disubstituted □-lactones 73c-e and 74 with high enantiomeric excesses. 3) Enantioselective formal synthesis of (+)-k252a: A seven-step synthesis, including diastereoselective aldol and alkylation reactions, of (+)-furanose 76 from 1,3-dioxolan-4-one 48 has been achieved in 47% overall yield.