Biogenetic syntheses of kopsijasminilam and deoxykopsijasminilam.
The hexacyclic ketoester 7, derived from cyclization of racemic minovincine (6), was reduced to two C-19 epimeric alcohols 8 and 9. Stereoelectronically controlled fragmentations of corresponding O-sulfonyl derivatives provided, respectively, the hexacyclic enamine 14 and, after oxidation of the olefin 16, the pentacyclic lactam 17 with a brigehead double bond. Formation of a carbamate, introduction of a second double bond at C-16, and conjugate reductive hydroxylation at C-20, or hydrogenation, gave the title products.
Kuehne
M E
ME
Department of Chemistry, University of Vermont, Burlington 05405, USA. mkuehne@zoo.uvm.edu
Li
Y L
YL
Wei
C Q
CQ
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D010084:Oxidation-Reduction; D013237:Stereoisomerism
D000470:Alkaloids; C416063:deoxykopsijasminilam; C416062:kopsijasminilam