Construction of trifluoromethyl-containing heterocycles from trifluoroacetimidoyl chlorides and derivatives

Recent advances in the direct synthesis of trifluoromethyl-containing heterocycles from trifluoroacetimidoyl chlorides (TFAICs) and derivatives, including trifluoroacetimidohydrazides (TFAIHs) and CF3-imidoyl sulfoxonium ylides (TFISYs), are systematically summarized and discussed. The cascade annulation reactions of trifluoromethyl-containing synthons with suitable coupling partners have emerged as a powerful and promising tool for the construction of a variety of trifluoromethyl-substituted heterocycles. Compared with other trifluoromethyl-containing building blocks, TFAICs and derivatives have notable merits of easy availability and handling, relative stability and safety, and high reactivity.