Preparation and utility of dianions from N-tert-butylthiophene-2-sulfonamide
摘要:
Metalation of N-tert-butylthiophene-2-sulfonamide with n-butyllithium occurs competitively at the 3- and 5-position of the thiophene ring. Equilibration of the initial mixture of carbanions or metalation with lithium diisopropylamide allows selective formation of the N,5-dilithiothiophenesulfonamide 7. This dianion is useful for the preparation of a number of 5-substituted thiophene-2-sulfonamides.