C. W. Jefford, K. Sienkiewicz, S. R. Thornton
Jul 4, 1994
Citations
0
Influential Citations
18
Citations
Journal
Tetrahedron Letters
Abstract
Abstract Diethyl L-glutamate hydrochloride ( 3 ) was converted to its N-pyrrole derivative 5 . Submission of 5 to butyryl chloride in boiling toluene gave the 2-butyryl derivative, and by treatment with NaBH 3 CN and ZnI 2 , the 2-butyl analogue 9 . Cyclization of 9 with BBr 3 afforded (5S)-3-butyl-5-ethoxycarbonyl-5,6-dihydro-8(7H)-indolizinone ( 10 ). Hydrogenation of 10 over Pd/C in acidified EtOH gave (3S,5S,9R)-3-butyl-5-ethoxycarbonylindolizidine. By successive reduction of the latter to the primary alcohol, formation of the chloride and reductive dechlorination with tributyltin hydride, (3S,5R,9R)-3-butyl-5-methylindolizidine, or (-)-monomorine, was obtained in 8 steps from 3 in a yield of 25%.