Chelation-Controlled Regioselection in Palladium-Catalyzed Carbonyl Allylation by 4-Pentene-1,3-Diol or Its Cyclic Carbonate

Abstract

With cat. PdCl₂(PhCN)₂ and SnCl₂, 4-pentene-1,3-diol caused regioselective carbonyl allylation at 3-position in DMF to produce 2-substituted 3-vinyltetrahydrofurans and/or 1-substituted 2-vinylbutane-1,4-diols, and cyclic carbonate of 4-pentene-1,3-diol caused regioselective carbonyl allylation at terminal 5-position in THF to produce 1-substituted 3-hexene-1,6-diols.

Notes

The coupling constant (J _112,113=0 Hz) between 2-H and 3-H in ¹H NMR (JEOL GX-270) of 2-phenyl-3-vinyltetrahydrofuran (5; R=Ph) suggested that the stereochemistry in a major isomer of all 2-substituted 3-vinyltetrahydrofurans 5 was trans (cis:trans=1:9).

Cyclic carbonate of 4-hexene-1,3-diol, namely 4-[(E)-2-propenyl]-1,3-dioxan-2-one caused the carbonyl allylation at room temperature neither in DMF nor in THF.