90821-46-8Relevant articles and documents
Reaction of Grignard reagents with α-epoxycyclopentanones. I. Stereoselective addition to the carbonyl group
Sepulveda, Jose,Soto, Salvador,Mestres, Ramon
, p. 233 - 236 (2007/10/02)
Ethyl-, vinyl- and ethynylmagnesium bromide reagents add, at -70 deg C-0 deg C, to the carbonyl groups of 2,3-epoxycyclopentanone 1 and 2,3-epoxy-3-methylcyclopentanone 2 through 100percent trans approach, to give high yields of the 1-substituted cis-epoxycyclopentanols 3 and 4.Hydrogenation of the ethynyl- and vinylcyclopentanols gave the ethylcyclopentanol, which shows that the stereochemical course of the reactions had been the same for all reagents.Addition of the Grignard reagents to the cyclopentanones 5 and 6 lead to the substituted cyclopentenols 7 and 8.Epoxidation of those with MCPBA gave 9:1 cis:trans mixtures of the corresponding epoxycyclopentanols.The major components 3c, 4a and 4c were isolated and identified with samples of the epoxycyclopentanols obtained by addition of Grignard reagents to the starting epoxyketones 1 and 2, thus allowing the assignment of cis configuration to be made.When yields are compared for conversion of cyclopentenones into substituted epoxycyclopentanols, the epoxidation-addition route becomes preferable to the addition-epoxidation one.Stereoselectivities compare favourable as well; single isomers are obtained by our procedure.