Charles E. Tucker

PREPARATION OF POLYFUNCTIONAL ARYL AND ALKENYL ZINC HALIDES FROM FUNCTIONALIZED UNSATURATED ORGANOLITHIUMS AND THEIR REACTIVITY IN CROSS-COUPLING AND CONJUGATED ADDITION REACTIONS

Abstract Functionalized aryl and alkenyl iodides undergo an iodine-lithium exchange at −90 to −80 °C providing polyfunctional organolithiums which are stable for a short time at these low temperatures and can be transmetalated to organozinc derivatives by the addition of zinc bromide. The resulting unsaturated organozinc halides can then be warmed up and are perfectly stable at 25 °C. They react directly with tosyl cyanide. In the presence of CuCN·2LiCl, they add in a Michael-fashion to alkylidenemalonates. In the presence of catalytic amounts of Pd(dba)2 and TPP or TFP, they undergo readily a cross-coupling at 25 °C with aryl and alkenyl iodides. The Pd-catalyzed coupling of arylzinc bromides with aryl triflates could also be achieved by using dppf as a ligand and 60 °C as reaction temperature.

Preparation of polyfunctional nitriles by the Cyanation of functionalized organozinc halides with p-toluenesulfonyl cyanide

Abstract Various alkyl, alkenyl, akynyl, benzylic, aromatic or heterocyclic organozinc halides bearing functional groups such as an ester, a boronic ester, a cyanide, a halide or a trialkoxysilyl group react under mild conditions with p-toluenesulfonyl cyanide affording polyfunctional nitriles in 69–93 % yields.

The chemistry of polyfunctional organozinc and copper reagents

Recent developments of the chemistry of polyfunctional organozinc and copper reagents applied to organic synthesis are presented.

Stereoselective synthesis of polyfunctional di- and trisubstituted cyclopentane derivatives using a new palladium catalyzed cyclization.

Abstract Various functionalized 5-hexenyl iodides undergo a radical ring closure to give cyclopentylmethylzinc iodides when treated with Et 2 Zn in the presence of PdCl 2 (dppf) (2 mol %). In the case of 4-substituted 5-hexenyl iodides trans -cyclopentanes are obtained (> 99 : 1) whereas 1-substituted-5-hexenyl iodides provide cis -cyclopentanes (ca. 80 : 20). The presence of a substituent at both positions considerably improves the cis stereoselectivity up to 95 : 5.

Preparation of polyfunctional diorganomercurials and their transmetallation to diorganozincs. Applications to the preparation of optically active secon

Abstract Two new methods of preparation of functionalized diorganomercurials have been developed. The first method involves a substitution reaction of (ICH 2 Their transmetallation with zinc dust (toluene, 80°C, 3–5 h) affords dialkylzincs which add enantioselectively to aldehydes in the presence of a ca

PREPARATION OF FUNCTIONALIZED ZINC AND COPPER ORGANOMETALLICS CONTAINING SULFUR FUNCTIONALITIES AT THE ALPHA OR GAMMA POSITION

Organolithiums stabilized by sulfurl are important carbanionic intermediates in organic synthesis. Their excellent abiity to form new carbon-carbon bonds combined with the easy conversion of the sulfur group to various other functionalities has led to numerous synthetic applications. However, the high reactivity of these reagents prohibits the presence of most functional groups in these organometallics. Herein, we report a new approach to a-thiocarbanions of zinc and copper allowing for the first time the presence of functional groups such as an ester- or a cyano-group in these compounds. We have recently found that the presence of an oxygen at the alpha position to a carbon-halide bond considerably facilitates the insertion of zinc into this carbon-halide bond, affording organozinc halides at the alpha position to oxygen.2 We have

Addition of polyfunctional and pure (E or Z) alkenylcopper and arylcopper compounds to alkylidenemalonates

Polyfunctional and stereochemically pure (E) or (Z) alkenylcopper reagents have been generated by carbocupration of terminal alkynes or by an iodine–lithium exchange reaction and have been found to add to various diethyl alkylidenemalonates, affording γ,δ-unsaturated esters in excellent yields.