Synthesis of Substituted Piperidines, Indolizidines, Quinolizidines, and Pyrrolizidines via a Cycloaddition Strategy Using Acetylenic Sulfones as Alkene Dipole Equivalents
作者:Thomas G. Back、Katsumasa Nakajima
DOI:10.1021/ol990592u
日期:1999.7.1
The conjugate additions of beta- and gamma-chloroamines to acetylenic sulfones afford enamine sulfones, which then undergo intramolecular alkylation to produce the corresponding cyclic enamines, This provides a convenient route to substituted piperidines, indolizidines, quinolizidines, and pyrrolizidines. The enantioselective total synthesis of the alkaloid (-)-indolizidine 167B (also named gephyrotoxin 167B) was thus achieved by the cycloaddition of (S)-2-(2-chloroethyl)pyrrolidine to 1-(p-toluenesulfonyl)-1-pentyne, followed by stereoselective reduction of the enamine moiety and reductive desulfonylation.
A Convenient New Route to Piperidines, Pyrrolizidines, Indolizidines, and Quinolizidines by Cyclization of Acetylenic Sulfones with β- and γ-Chloroamines. Enantioselective Total Synthesis of Indolizidines <b>(</b><b>−</b><b>)-167B</b>, <b>(</b><b>−</b><b>)-209D</b>, <b>(</b><b>−</b><b>)-209B</b>, and <b>(</b><b>−</b><b>)-207A</b>
作者:Thomas G. Back、Katsumasa Nakajima
DOI:10.1021/jo000080p
日期:2000.7.1
the corresponding 2- or 2,6-disubstituted piperidines, while 2-(chloromethyl)pyrrolidines, 2-(2-chloroethyl)pyrrolidines, 2-(chloromethyl)piperidines, and 2-(2-chloroethyl)piperidines produced the corresponding 3-substituted pyrrolizidines, 5- or 3-substituted indolizidines, and 4-substituted quinolizidines, respectively. 8-Methyl-5-substituted indolizidines were also prepared from the appropriate methyl-substituted