3-substituted furan systems can be obtained by alkylation of 3-lithium furans with various electrophiles in the presence of hexamethylphosphoric acid triamide in good yields. The 2- or 5-position of 3-methyl furan is blocked with high regioselectivity by silylation. After metalation and alkylation of the remaining free α-position and subsequent desilylation the 2,3- and 2,4-disubstituted furans are
Use of 2-phenylsulphonyl cyclic ethers in the preparation of tetrahydropyran and tetrahydrofuran acetals and in some glycosidation reactions.
作者:Dearg S. Brown、Steven V. Ley、Sadie Vile、Mervyn Thompson
DOI:10.1016/s0040-4020(01)86389-4
日期:1991.1
2-Phenylsulphonyl cyclic ethers undergo facile displacement of the sulphonyl group by alcohols, in the presence of magnesium bromide etherate and sodium bicarbonate in tetrahydrofuran, to give goodyields of the corresponding acetals.