Prins cyclization to tetrahydrofuran units of polyether antibiotics: Remarkable siloxy effect for stereocontrolled cyclization
作者:Koichi Mikami、Masaki Shimizu
DOI:10.1016/s0040-4039(00)60962-0
日期:1992.10
A novel route to substituted tetrahydrofurans is described, which is based on the Lewis acid-promoted Prins cyclization with side chain formation of CC bond. Bishomoallylic silyl ethers, rather than the (chloro)benzyl ethers and esters, provide selectively tetrahydrofurans, indicating the siloxy effect for facilitating the cyclization.
Silyl triflate-catalyzed oxonium-ene reaction of lactol allylic ethers: A new and stereocontrolled route to substituted oxygen heterocycles
作者:Koichi Mikami、Hiroyuki Kishino
DOI:10.1016/0040-4039(96)00646-6
日期:1996.5
An ene-type reaction of lactol-derived allylicethers is found to be catalyzed by silyl triflates to afford the propionaldehyde-substituted tetrahydrofuranes and -pyrans stereoselectively via the cyclic oxonium ion intermediate and allyloxysilyl moiety derived from the lactol allylicethers.