Unexpected reactivity of imidazo[2,1-b]thiazolines with organometallic reagents

The reaction of imidazo[2,1-b]thiazolines with various organometallic reage nts is described, Nucleophilic attack of organolithium reagents on sulfur o ccurs with extrusion of ethylene to produce 5-thioalkyl- or 2-thioarylimida zoles. The outcome with Grignard reagents, however, is less predictable, wi th some reagents adding at sulfur and others reacting at C-2 or not at all.