Unexpected Formation of 3-Methylsulfanyl-2-phenyl-2-cyclobutenone in the Reaction of l,3-Dilithio-2-propynylbenzene with Methoxymethyl Isothiocyanate

摘要

We recently found[1]that the reaction of 1,3-di-lithiated 2-propynylbenzene with methyl isothio-cyanate,followed by treatment of the primary adduct with a proton donor,base,and methyl iodide,results in formation of three isomeric products:N-methyl-3-methylsulfan-yl-2-phenyl-2-cyclobuten-1 -imine,N,3-dimethyl-4-meth-ylene-3-phenylthietan-2-imine,and 2-dimethylamino-3-phenylthiophene at a ratio of 68:16:16(overall yield 68-77%).