Synthesis of 5,7-Dichloro-6-azaindoles and Functionalization via a Highly Selective Lithium-Chlorine Exchange

Abstract

The synthesis of a range of novel 5,7-dichloro-6-azaindoles through the use of a Fischer cyclization with pyridine hydrochloride in N-methylpyrrolidin-2-one is described. Dichloro-6-azaindoles are versatile compounds that can be selectively substituted through a palladium-catalyzed cross-coupling reaction or a high-yielding lithium-chlorine exchange.

Key words

azaindole - pyrrolopyridine - Fischer cyclizations - metalations - palladium

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12

The use of a condenser is not recommended.

13

Typically, aminopyridine 1 was isolated in less than 5%.

22

Starting material 6 was observed in less than 5% on the ^¹H NMR of the unpurified reaction mixture.