90314-46-8Relevant articles and documents
Reaction of Grignard reagents with α-epoxycyclopentanones. II. The opening of the oxirane ring
Sepulveda, Jose,Soto, Salvador,Mestres, Ramon
, p. 237 - 239 (2007/10/02)
By reaction of ethyl-, vinyl- and ethynylmagnesium bromides with 2,3-epoxycyclopentanone 1 at -70 deg C and heating of the reaction mixture at 40 deg C, the epoxycyclopentanols 3 were obtained only in trace amounts, whereas the bromodiols 5 formed in higher than 75percent isolated yields.The presence of cis-vicinal diol in all bromodiols is clear from the obtention of O-isopropylidene derivatives 6.In the same conditions as for epoxycyclopentanone 1, the epoxyketone 2 reacted in a much different way, giving hydroxycyclopentanones 7 (50-60percent), cyclopentendiols 8 (18-37percent) and methylidenecyclopentanediols 9 (small to trace amounts).When an excess of the ethyl- or ethynylmagnesium bromide was used, epoxycyclopentanone 2 gave the dialkyldiols 10a (58percent) and 10c (62percent).The configuration of the cyclopentenediol 8a was determined by preparation of the O-isopropylidene derivative.For the other products we have made the assignment taking into account negative experiments and mechanistic considerations.
