FUROPYRIDINES .12. REACTION OF 3-BROMO, 2-PHENYLTHIO AND 2-PHENYLTHIO-3-BROMO DERIVATIVES OF FURO[2,3-B]PYRIDINE, FURO[3,2-B]PYRIDINE, FURO[2,3-C]PYRIDINE AND FURO[3,2-C]PYRIDINE WITH SEVERAL ALKYLLITHIUMS

This paper describes reactions of 3-bromo- la-d, 2-phenylthio- 5a-d and 2-phenylthio-3-bromofuropyridines 6a-d with n-butyl-, t-butyl- and methyllithium and lithioacetonitrile. Lithiation of compounds la-d with n-butyl- or methyllithium gave the parent furopyridines 2a-d and o-ethynylpyridinols 3a-d. Reaction of compounds 5a-d with methyllithium afforded o-(phenylthioethynyl)pyridinols 7a-d, which were also yielded by reaction of compounds 6a-d with t-butyl- or methyllithium. The phenylthio group in compounds 7a-d were substituted with t-butyl group by the reaction with excess t-butyllithium. In contrast, 2-phenylthio group in compounds 5a-d and 6a-d was substituted with cyanomethyl group by reaction with lithioacetonitrile to give compounds 11a-d and 10b,c respectively.