Abstract
Starting from cyclopropylacetylene and 3,3-dimethylbut-1-yne, and an imidoyl chloride 5 , the alkynyl imines 6 were prepared and then converted into propyne iminium triflates 7 by N-methylation. These electron-deficient acetylenes were found to be reactive dienophiles in Diels-Alder reactions with cyclopentadiene, furan, 2,3-dimethylbuta-1,3-diene, and anthracene. Reduction of the iminium function, which is present in the cycloaddition products, generates tertiary amines. In this manner, norbornadiene (8 , 9 ), 7-oxanorbornadiene (10 , 11 ), cyclohexa-1,4-diene (12 ), benzene (13 , 14 ), and dibenzobarrelene (15 , 16 ) derivatives with a novel vicinal substitution pattern were obtained.
Key words
alkynes - imines - iminium salts - cycloadditions - Diels-Alder reactions
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