INTRAMOLECULAR REACTIONS OF FISCHER CARBENE COMPLEXES WITH ALKYNES AND A MECHANISTIC STUDY OF THE INTERCEPTION OF REACTIVE INTERMEDIATES WITH ADDED ACETYLENES
Ba. Anderson et al., INTRAMOLECULAR REACTIONS OF FISCHER CARBENE COMPLEXES WITH ALKYNES AND A MECHANISTIC STUDY OF THE INTERCEPTION OF REACTIVE INTERMEDIATES WITH ADDED ACETYLENES, Journal of the American Chemical Society, 115(23), 1993, pp. 10671-10687
The reactions of 1-(4-hexynyl)methoxymethylenepentacarbonyl complexes
11 of the group 6 metals with alkynes lead to phenol and cyclopentened
ione products, both of which are the result of cyclization with one mo
lecule of the external alkyne and the internal alkyne in the carbene c
omplex. All four of the possible phenol products of this reaction were
independently synthesized, and the product distribution among the fou
r isomers and the cyclopentenedione was investigated as a function of
solvent, concentration, and the nature of the metal. The results of th
ese experiments suggest that the phenol 13 arises from a vinyl carbene
complexed intermediate and that the phenol 16 and cyclopentenedione 1
2 arise from a vinyl ketene complexed intermediate. This was confirmed
by a series of methanol trapping experiments and by the isolation, ch
aracterization, and study of the chemistry of the proposed vinyl keten
e complex.