Effect of High Pressure on the Cycloaddition of Difluoroallene and (Z)-β-Deuteriostyrene

Article abstract of DOI:10.1021/jo00289a054

1,1-Difluoroallene and (Z)-β-deuteriostyrene undergo a <2+2> cycloaddition to form two regioisomeric products, (Z)- and (E)-4-deuterio-2,2-difluoro-3-phenyl-1-methylenecyclobutane, 1 (major), and (Z)- and (E)-2-deuterio-3-phenyl-1-(difluoromethylene)cyclobutane, 2 (minor), each with different degrees of stereochemical retention.The imposition of high pressure (2-13 kbar) on the reaction alters both the regioselectivity and the stereoselectivity on the reaction significantly, decreasing the former und increasing the latter.A mechanism involving two kinetically distinct diradical intermediates is proposed to rationalize the results.