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Dynamic control of dichlorocarbene addition to cyclopropene


  • Dedicated to Professor Robert A. Moss on the occasion of his 70th birthday.

Dina C. Merrer, Department of Chemistry, Barnard College, 3009 Broadway, New York, NY 10027, USA.



The addition of dichlorocarbene to cyclopropene has been studied with direct dynamics quasiclassical trajectories using B3LYP/6-31G*. The trajectories yielded 1,1-dichlorobicyclo[1.1.0]butane and 1,1-dichloro-1,3-butadiene in a ratio of 4.7:1, which is consistent with the experimental ratio of 4:1. The large majority of trajectories formed products within 100 fs of the start of the trajectory and proceeded in a concerted manner to the bicyclobutane or butadiene; no zwitterion or biradical intermediate was observed. Eight trajectories generated bicyclobutane and subsequently dissociated chloride to form an ion pair, which recombined to form 2,3-dichlorocyclobutene. The lifetime of the ion pair averaged 95 fs, which was too short to be considered an intermediate, consistent with previous calculations that characterized the ion pair as a transition state. This study lends strong support to the previous proposition that the addition of CCl2 to cyclopropene is controlled by dynamic effects. Copyright © 2011 John Wiley & Sons, Ltd.