Synthesis of (�)-trans-2,5-Dialkylpyrrolidines from theLukes-?orm Dilactam: Efficient Preparation of (�)-trans-2-Butyl-5-heptylpyrrolidine and Analogs Present in Ant Venoms
作者:Wieslaw Gessner、Kimio Takahashi、Arnold Brossi、Marek Kowalski、Michael A. Kaliner
DOI:10.1002/hlca.19870700805
日期:1987.12.16
A 7-step synthesis of (±)-trans-2-butyl-5-heptylpyrrolidine (14) from the Lukes-Šorm dilactam 1 was accomplished in 6% overall yield without counting for a reconversion of cis-isomer 13 into trans-isomer 14 which was also accomplished. Reduction of pyrroline 12, the precursor of 14, with NaBH4 afforded a 1:1 mixture of cis-isomer 13 and trans-isomer 14 separated by chromatography. Reductive N-methylation
centre at C-2 of the pyrrolidine ring. The first enantioselective synthesis of (+)-(S)-trans-2-heptyl-5-ethyl-pyrrolidine 9, a component of the venom of the ant Solenopsispunctaticeps served as an example of the method. Bothenantiomers of cis-2-heptyl-5-ethyl pyrrolidine 13 were obtained from the minor diastereomers 7 and 8 which were formed on reaction of oxazolidines 5a and 5b with Grignard reagents