- Department of Chemistry, North-Eastern Hill University, Shillong 793 003, Meghalaya India
The oxoketene dithioacetals undergo regioselective 1,2-addition with 2-lithiomethyl-4-methylthiazole and 2-lithiomethylthiazoline (3) to afford the carbinol acetals which on borontrifluoride etherate assisted cyclization yield the corresponding substituted and annelated 3-methyl-5- methylthiothiazolo[3,2-a.] pyridinium tetrafluoroborates and the dihydro derivatives respectively in good yields. The corresponding 2-methyl-5-phenylthiazole however underwent both nuclear and side chain deprotonation and yielded a mixture of products under similar reaction conditions.
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