Hydroamination of 2-Ethynylpyrroles

SCHEME 2.68 Addition of secondary amines to 2-benzoylethynyl-4,5,6,7-tetrahydroin-doles. 

SCHEME 2.69 Addition of dimethylamine to ethyl-3-(4,5,6,7-tetrahydroindol-2-yl)-2-pro-pynoates. 

The reaction of ethyl 3-(NH-4,5,6,7-tetrahydroindole-2-yl)-2-propynoate with diethylamine is accompanied by intramolecular cyclization of the primary adduct to pyrroloindole, their ratio being 1 1. Upon separation of this mixture (AI2O3), the adduct cyclizes completely to pyrroloindole. 

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