Asymmetric synthesis with .alpha.,.beta.-bis[(methoxymethyl)oxy] ketones. Enantioselective total synthesis of natural (+)-indolizidine 195B (bicyclic gephyrotoxin 195B) and (-)-pinidine and their enantiomers from a common chiral synthon
Asymmetric synthesis with .alpha.,.beta.-bis[(methoxymethyl)oxy] ketones. Enantioselective total synthesis of natural (+)-indolizidine 195B (bicyclic gephyrotoxin 195B) and (-)-pinidine and their enantiomers from a common chiral synthon
Synergistic effect of multichiral centres. Chelation control vs. acetal template in 1,3-asymmetric induction
作者:Yoshinori Yamamoto、Jun-ichi Yamada
DOI:10.1039/c39870001218
日期:——
The allylation of the β-siloxyacetal (5), (S–R,R isomer) in the presence of TiCl4 gave the chelation adduct (6) with very high selectivity, while the (R–R,R) isomer (8) also produced the chelation adduct (9), indicating that the 1,3-asymmetricinduction is dictated by chelation rather than the acetaltemplate.
Asymmetric synthesis with .alpha.,.beta.-bis[(methoxymethyl)oxy] ketones. Enantioselective total synthesis of natural (+)-indolizidine 195B (bicyclic gephyrotoxin 195B) and (-)-pinidine and their enantiomers from a common chiral synthon