Formation of cyclic allenes and cumulenes by cooperative addition of frustrated Lewis pairs to conjugated enynes and diynes

Article abstract of DOI:10.1002/anie.200906697

Eight, not six: The intramolecular frustrated Lewis pair 1 reacts with conjugated enynes and diynes by 1, 4-addition to yield the corresponding eight-membered cyclic allenes 2 and cumulenes 3, respectively. The thermodynamically more favorable 1, 2-addition (formation of six-mem bered-ring products) is not observed, which indicates that the observed addition is a kinetically controlled reaction. (Figure Presented)