Benzyl chlorides react with t-butyl-lithium in a mixture of pentane and hexane to give neopentylbenzenes, XC6H4·CH2But. Yields were (X =) H, 75; o-Me, 25; m-Me, 55; p-Me, 62; m-F, 70; p-F, 70; m-Cl, 60; p-Cl, 69; p-Br, 60%.
Nickel-mediated cross-coupling of unactivated neopentyl iodides with organozincs
作者:Kwangyong Park、Kaixu Yuan、William J. Scott
DOI:10.1021/jo00070a022
日期:1993.8
(dppf)NiCl2 catalyzes the cross-coupling of unactivated primary neopentyl iodides with diorganozinc reagents. The zinc nucleophiles are formed by the treatment of ZnCl2.dioxane with 2 mol equiv of a Grignard reagent in an ethereal solvent. The cross-coupling works optimally for diorganozincs formed from aryl chlorides or CH3MgCl. Use of aryl bromides can cause reduction and/or reductive dimerization of the electrophile. The analogous reaction with (CH3)2CuMgCl in either the presence or the absence of Group 10 metal catalysts failed to afford reasonable yields of cross-coupled products. The diorganozinc methodology overcomes many of the side reactions observed with the (dppf)-NiCl2-mediated cross-coupling of Grignard reagents.