Novel azido fatty acid ester derivatives from conjugated C 18 enynoate

Abstract

Methyl octadec-11 Z-en-9-ynoate ( 1) was epoxidized to give methyl 11,12- Z-epoxy-octadec-9-ynoate ( 2, 81%). Acid catalyzed ring opening of the epoxy ring of compound 2 gave methyl 11,12-dihydroxy-octadec-9-ynoate ( 3, 80%). The latter was treated with mesyl chloride to yield methyl 11,12-dimesyloxy-octadec-9-ynoate ( 4, 76%). Reaction of compound 4 with sodium azide furnished methyl 11-azido-12-mesyloxy-octadec-9-ynoate ( 5a, 49%) and methyl 11-azido-octadec-11 E-en-9-ynoate ( 5b, 24%). Compound 2 was semi-hydrogenated over Lindlar catalyst to give methyl 11,12- Z-epoxy-octadec-9 Z-enoate ( 6, 90%). This allylic epoxy fatty ester ( 6) was reacted with sodium azide to give a mixture of methyl 11-azido-12-hydroxy-octadec-9 Z-enoate ( 7a) and methyl 9-azido-12-hydroxy-octadec-9 E-enoate ( 7b), which could not be separated into individual components by silica chromatography. Chromic acid oxidation of the mixture of compounds 7a and 7b furnished methyl 9-azido-12-oxo-octadec-10 E-enoate ( 8, 42% based on amount of compound 6 used) and an intractable mixture of polar compounds. The various products were characterized by NMR spectroscopic and mass spectral analyses.