Evaluation of phenylorganotellurium compounds as radical precursors in dialkylzinc-mediated radical addition to CN double bonds

Efficient preparation of unsymmetrical alkyl–aryl tellurides via a nickel-catalyzed reductive coupling strategy

A selective cross-coupling between unactivated alkyl bromides and diaryl tellurides through reductive nickel-catalysis is described, which efficiently led to unsymmetrical alkyl–aryl tellurides.

Radical migration-addition of N-tert-butanesulfinyl imines with organozinc reagents

A novel migration-addition sequence was discovered for the reaction of enantioenriched N-tert-butanesulfinyl iminoacetate 1a with functionalized benzylzinc bromide reagents, producing tert-leucine derivatives in excellent diastereoselectivity (dr 98:2). The absolute configurations of two new chiral centers were unambiguously assigned by chemical transformations and X-ray crystallography. In addition, the regio- and diastereoselectivities of this novel reaction were both explained through the key N-sulfinamine intermediate M6 generated by the tert-butyl radical attack on the imine. Computational analysis of this reaction process, which was performed at the B3LYP/6-311++G(3df,2p)//B3LYP/6-31G*-LANL2DZ level, also supported our proposed two-stage mechanism.

Aminomethylation of Michael acceptors: complementary radical and polar approaches mediated by dialkylzincs

Phtalimidomethyl iodide and substituted maleimidomethyl iodide were used as radical precursors in dialkylzinc-mediated radical addition to diethyl fumarate. The reactions led stereoselectively to functionalized pyrrolizidines. The radical mechanism was supported by spin-trapping experiments and rationalized by theoretical calculations. Radical additions, on the one hand, and carbozincation followed by transmetalation with copper(I), on the other, were shown to be complementary methods to achieve the formal aminomethylation of activated unsaturated compounds.

Me(2)Zn as a radical source in Reformatsky-type reactions

Experimental evidence for the generation of radicals by Me(2)Zn used in Reformatsky reactions was unequivocally established with a radical trap.

Autoxidation of Organoboranes and Related Organometallics: Radicals and their Ramifications

The identification, 50 years ago, of the autoxidation products of organoboranes as organoperoxyboranes, and of the mechanism of the reaction as a radical chain, has had far-reaching consequences in organometallic and organic chemistry in the identification of organic radicals and of other radical reactions, in the use of organoboron compounds in synthesis and catalysis, in the parallel chemistry of other metals (particularly, currently, of zinc), and of the behaviour of metals as hydrogen equivalents. This review traces the course of some of those developments in the radical chemistry of compounds in which oxygen forms a bond with boron and related metals, and summarises the present position.