摘要:
The boron trifluoride-methanol derivatization of methyl 9,12-octadecadienoate was studied. This methylene-interrupted diene was reacted with 50% BF3-MeOH for 15 h at 0-5 degrees C and the four monomethoxy and two dimethoxy derivatives thus obtained were analyzed by gas chromatography-mass spectrometry. The only dimethoxy adducts observed were characterized as methyl 9,12-dimethoxyoctadecanoate and methyl 10,13-dimethoxyoctadecanoate. The complete regiospecificity observed in the formation of the dimethoxy adducts is best explained by a common O-methyltetrahydrofuranium ion as the only intermediate under these reaction conditions. (C) 1997 Elsevier Science Ireland Ltd.