Stereoselective synthesis of tetrasubstituted alkenes via a sequential carbocupration and a new sulfur-lithium exchange.
We have designed a new sequential carbocupration and sulfur-lithium exchange that leads stereo- and regioselectively to trisubstituted alkenyllithiums. Subsequent trapping with various electrophiles yields tetrasubstituted olefins with good control of the double-bond geometry (E/Z ratio up to 99:1). The novel sulfur-lithium exchange could be extended to the stereoselective preparation of Z-styryl lithium derivatives with almost complete retention of the double-bond geometry.
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany.
Andreas
A
Unsinn
Cora
C
Dunst
Paul
P
Knochel
alkenes; carbometalation; copper; regioselectivity; stereoselectivity