Reaction of mono-epoxidized conjugated linoleic acid ester with boron trifluoride etherate complex.
The reaction of methyl 11,12-E-epoxy-9Z-octadecenoate (1) with boron trifluoride etherate furnished a mixture of methyl 12-oxo-10E-octadecenoate (3a) and methyl 11-oxo-9E-octadecenoate (3b) in 66% yield. Methyl 9,10-Z-epoxy-11E-octadecenoate (2) with boron trifluoride etherate furnished a mixture of methyl 9-oxo-10E-octadecenoate (4a, 45%) and methyl 10-oxo-11E-octadecenoate (4b, 19%). A plausible mechanism is proposed for these reactions, which involves the attack on the epoxy ring system by BF3, followed by deprotonation, oxo formation, and double bond migration to give a mixture of two positional alpha,beta-unsaturated C18 enone ester derivatives (3a/3b, 4a/4b). The structures of these C18 enone ester derivatives (3a/3b, 4a/4b) were identified by a combination of NMR spectroscopic and mass spectrometric analyses.
Jie
Marcel S F Lie Ken
MS
Department of Chemistry, The University of Hong Kong, Hong Kong, SAR, People's Republic of China. hrsclkj@hkucc.hku.hk
Lam
Corey N W
CN
D001880:Boranes / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry; D004952:Esters / Q000737:chemistry; D044243:Linoleic Acids, Conjugated / Q000737:chemistry*; D015394:Molecular Structure
D001880:Boranes; D004852:Epoxy Compounds; D004952:Esters; D044243:Linoleic Acids, Conjugated; C101707:boron trifluoride etherate