Synthesis of exo enol ether-cyclic ketal isomers of substituted furanmethanol structures related to marine furanocembranoids
作者:Yi Li、Gerald Pattenden、Joseph Rogers
DOI:10.1016/j.tetlet.2009.12.131
日期:2010.3
of the epoxide 10 with p-TSA in MeOH produces the enol ether cyclic ketal 12, which is rapidly isomerised to the furanmethanol ether 15, isolated in 80% yield. By contrast, when the propanol-substituted furan epoxide 23 was kept in CDCl3 containing traces of HCl for 2 h, a 3:2 mixture of Z- and E-isomers of the enol ether spiro ketals 25a and 25b was produced in >92% yield; after 24 h this mixture of