Reactions of 1,1-Dihaloalkenes with Triorganozincates: A Novel Method for the Preparation of Alkenylzinc Species Associated with Carbon-Carbon Bond Formation

Article abstract of DOI:10.1021/jo00070a027

Lithium trialkylzincates react with 1,1-dibromoalkenes 1 and 1-bromo-1-chloroalkenes 2 at -85 deg C in THF to give 1-bromoalkenes 5 and 1-chloroalkenes 7, respectively, upon hydrolysis.The intermediate (1-haloalkenyl)zincates 4 and 6 are stable at low temperature but, when allowed to warm to 0 deg C, they undergo a 1,2-alkyl migration reaction to afford alkenylzinc species 10.A variety of alkylation products 11 are obtained by the hydrolysis of 10.In the presence of (Ph3P)2Pd (5 molpercent), alkenylzinc species 10 react smoothly with organic halides (AcCl, EtOCOCl, CH2=CH(Me)Br, PhBr) to yield the corresponding coupling products 13-16.