A Computational Study of Radical Haloacetal Cyclizations Controlled by the Acetal Center

摘要

The stereochemical outcome of the radical haloacetal cyclization reaction (Ueno-Stork reaction) has been examined by ab initio and other molecular orbital techniques. It was found that the stereochemistry of 5-exo- and 6-exo trig cyclizations can be accurately predicted from calculations using moderate levels of theory (UHF/6-311G~** or B3LYP/6-311G~**). A simplified computational procedure, easily run on a standard desktop computer, has been developed that provides excellent predictve ability for the stereochemical outcome for the reactions in question. Interestingly, a novel twist transition state has been identified for the firs time in 5-exo-trig radical cyclization reactions.