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.

Regioselective functionalization of the thiazole scaffold using TMPMgCl·LiCl and TMP2Zn·2MgCl2·2LiCl.

A general method for the synthesis of 2,4,5-trisubstituted thiazoles has been developed. Starting from commercially available 2-bromothiazole, successive metalations using TMPMgCl·LiCl or TMP(2)Zn·2MgCl(2)·2LiCl lead to the corresponding magnesated or zincated thiazoles which readily react with various electrophiles providing highly functionalized thiazoles.

Preparation of heterocyclic amines by an oxidative amination of zinc organometallics mediated by Cu(I): a new oxidative cycloamination for the preparation of annulated indole derivatives.

Functionalized heterocyclic zinc reagents are easily aminated by an oxidative amination reaction of zinc amidocuprates prepared from various lithium amides. For the oxidation step, PhI(OAc)(2) proved to be the best reagent. The required heterocyclic zinc organometallics can be prepared either by direct metalation, by magnesium insertion in the presence of ZnCl(2), or by transmetalation of a suitable magnesium reagent.

Oxidative amination of heteroaromatic zinc reagents mediated by PhI(OAc)(2).

The oxidative amination of functionalized heterocycles has been achieved by using readily available heterocyclic zinc reagents and lithium amides. PhI(OAc)(2) proved to be a suitable reagent for this oxidative amination.