Nickel-catalyzed multi-component coupling reaction of aldimine, alkyne, and dimethylzinc via dimerization of butadiene

In the presence of a Ni/phosphine ligand catalyst, dimethylzinc, alkyne, butadiene, aldehyde, and primary amine were successively combined via dimerization of butadiene to provide (3E,7E,10Z)-dodecatrienylamine in good yields with excellent regio and stereoselectivities.     

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

Diethylzinc-mediated radical addition to CN bonds was investigated in the presence of phenylorganotellurium compounds as radical precursors. As group transfer agents, secondary alkyl phenyl tellurides were shown to be about twice as reactive as the corresponding alkyl iodides towards ethyl radical. Their use was proven to be advantageous regarding both chemoselectivity and yield. The replacement of diethylzinc by dimethylzinc, offers no advantage in these reactions.     

Direct aminoalkylation of cycloalkanes through dimethylzinc-initiated radical process

Cycloalkyl radicals were directly generated from cycloalkanes via C-H bond cleavage by the action of dimethylzinc-air and underwent an addition reaction with N-tosylimines, giving aminoalkylation products in fair to high yields.     

α,β-Unsaturated diesters: radical acceptors in dialkylzinc-mediated tandem radical addition/aldol condensation. A straightforward synthesis of rac-nephrosteranic acid

The sequence involving conjugate radical addition/aldol condensation/lactonization is a high yielding route to di- and tri-substituted γ-lactones starting from fumaric or maleic diesters. The reactions are mediated with dialkylzincs. The domino process relies on the ability of dialkylzinc to transform α-alkoxycarbonylalkyl radicals into zinc enolates. Compared to diethylzinc, dimethylzinc enables the use of a wider range of alkyl radical precursors. In addition, dimethylzinc is a convenient source of methyl radical, which leads to a straightforward synthesis of methylated derivatives related to α-methyl-paraconic acids.     

Diastereoselective addition of organozinc reagents to 2-alkyl-3-(arylsulfanyl)propanals

The preparation of compounds incorporating the 3-hydroxy-2-methyl-1-alkyl moiety of high diastereomeric purity is described. Such compounds can serve as potential building blocks for the preparation of several kinds of natural products. Diastereoselective synthesis of two potential pine sawfly pheromone components, one the pure racemic threo-isomer of 3-methylpentadecan-2-ol and the other the racemic erythro-isomer of 3-methyltridecan-2-ol are described. The diastereoselective addition of R₂Zn (R=Me, Et and n-Bu) to several 2-alkyl-3-(arylsulfanyl)propanals in the presence of a Lewis acid and CH₂Cl₂ as solvent was studied. An excellent diastereomeric ratio (95/5 anti-Cram/Cram) was obtained with 2-[(phenylsulfanyl)methyl]pentanal, 2-[(phenylsulfanyl)methyl]decanal and 2-[(phenylsulfanyl)methyl]dodecanal and Me₂Zn in the presence of TiCl₄.