H. Monti et al., ZNI2 CATALYZED [2-BUTYN-2-ONE - CONFIRMATION OF A CYCLOBUTENE BY-PRODUCT FORMATION(2] VERSUS [3+2] CYCLOADDITION OF AN ALLYLTRIMETHYLSILANEWITH 3), Tetrahedron letters, 35(19), 1994, pp. 3073-3076
NMR experiments unequivocally show that the by-product obtained from t
he ZnI2-promoted reaction of an allyltrimethylsilane with 3-butyn-2-on
e is a [2+2] cycloaddition compound. This fact corroborates our previo
usly described assignment. In the experimental conditions used, the re
action occurs without 13-silyl shift.