Treatment of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha -chlorocarboxylic acid chlorides resulted in chemo- and regioselective formation of 6-chloro-3,5-dioxo esters, which were regioselectively converted into functionalised 3(2 H)furanones. Chemo- and regioselective condensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha -chloroacetic dimethyl acetal afforded 6-chloro-5-methoxy-3-oxo esters, which could be regio- and stereoselectively transformed into 2-alkylidene-4-methoxytetrahydrofurans.
Synthesis of (tetrahydrofuran-2-yl)acetates based on a ‘cyclization/hydrogenation/enzymatic kinetic resolution’ strategy
作者:Esen Bellur、Ilia Freifeld、Dominique Böttcher、Uwe T. Bornscheuer、Peter Langer
DOI:10.1016/j.tet.2006.03.077
日期:2006.7
A variety of (tetrahydrofuran-2-yl)acetates and (pyrrolidin-2-yl)acetates have been prepared by hydrogenation of 2-alkylidene-tetrahydrofurans and 2-alkylidenepyrrolidines, which are readily available by cyclization reactions of 1,3-dicarbonyl dianions (free dianions') or 1,3-bis-silyl enol ethers ('masked dianions') with 1,2-dielectrophiles. The enzymatic kinetic resolution of (tetrahydrofuran-2-yl)acetates with recombinant esterase Est56 proceeded with excellent enantioselectivities (E > 100). (c) 2006 Elsevier Ltd. All rights reserved.