Synthesis of Cyclic Ethers Utilizing a Cyclization–Fragmentation Strategy
作者:Denise A. Ockey、David R. Lane、Juliette A. Seeley、Neil E. Schore
DOI:10.1016/s0040-4020(99)01063-7
日期:2000.1
A variety of cyclic ethers have been prepared via both solution phase and polymer-supported sequences of 3+2 cycloaddition of nitrile oxides to alkenes and dienes to give isoxazolines, followed by electrophile-induced cyclization. Library generation by alkylative elaboration of isoxazolines was unsuccessful, but both simple and substituteddienes were found suitable for polymer-supported formation
Deprotonation and subsequent alkylation of 3,4-dihydro-6-(para-toluenesulfonylmethyl)-2H-pyran gives monoalkylated products in good yields, with excellent α selectivity. The alkylation succeeds not only for reactive haloalkanes, but also for simple primary and secondary alkyl bromides. Desulfonylation with sodium amalgam provides a new and simple route to substituted dihydropyrans.