THE PREPARATION OF 1,3-DIZINCAPROPANES VIA A BORON-ZINC TRANSMETALATION

The reaction of 1,3-diethylborylpropane and the corresponding 3-mercur io derivatives were prepared by hydroboration of the allylic precursor and were treated with diethylzinc leading to the corresponding 1,3-bi metallic reagents which, based on their sharp NMR signals, were tentat ively considered as eight-membered rings. Their reaction with reactive electrophiles like allylic bromides or propargyl bromide, benzoyl chl oride and ethyl propiolate in the presence of CuCN . 2LiCl provided th e desired 1,3-adducts in fair to good yields. These sensitive 1,3-dime tallics proved not to be suited for reactions with less reactive organ ic electrophiles, and hydride-transfer reactions were observed. (C) 19 98 Elsevier Science S.A. All rights reserved.