Phenyl(trifluoromethanesulfonyl)acetyIene, prepared from the lithium salt of phenylacetylene and trifluoromethanesulfonic acid anhydride, undergoes exceptionally facile Diels-Alder reactions with tetraphenylcyclopentadienone, 1,3-diphenylisobenzofuran, cyclopentadiene, and 1,3-cyclohexadiene. The rates of these reactions and those of the corresponding reactions with other C6H5C≡CX derivatives were measured and compared. The rate of reaction of phenyl(trifluoromethanesulfonyl)acetylene with cyclopentadiene in ethyl acetate at room temperature was found to be 1.7 times as fast as the rate of reaction of dimethyl acetylenedicarboxylate with this diene. The reasons for the remarkable dienophilicity of phenyl(trifluoromethanesulfonyl)acetylene are discussed.
ASJC Scopus subject areas
- Organic Chemistry