Thiocarbonyl fluoride generated in situ from difluorocarbene for cyclization of vicinal X-H substituted amines (X = N, O or S)

•Thiocarbonyl fluoride generated in situ from difluorocarbene acts as a thiocarbonyl source for cyclization.•The cyclization of X-H substituted amines provides imidazolidine-, oxazolidine- and thiazolidine-2-thiones.•The NH bond in products remains intact in the reactions involving the generation of difluorocarbene.