Asymmetric [2,3] Wittig rearrangement of crotyl furfuryl ethers

Abstract

Asymmetric Wittig rearrangement of crotyl furfuryl ethers was investigated in diastereo- and enantioselective manners. Both (2 S,3 Z)- and (2 S,3 E)-3-penten-2-yl furfuryl ethers 3 and 9 rearranged with complete chirality transfer to give the syn- and anti-isomers 4 and 10, respectively. Enantioselective Wittig rearrangement of both ( Z)-and ( E)-crotyl furfuryl ethers 15 and 17 using butyllithium and (−)-sparteine was examined to afford (1 S,2 R)-1-(2-furyl)-2-methyl-3-buten-ol 16 in up to 43% ee.