Furopyridines. XII . Reaction of 3‐bromo, 2‐phenylthio and 2‐phenylthio‐3‐bromo derivatives of furo[2,3‐ b ]‐, furo[3,2‐ b ]‐, furo[2,3‐ c ]‐ and furo[3,2‐ c ]pyridine with several alkyllithiums

This paper describes reactions of 3‐bromo‐ 1a‐d , 2‐phenylthio‐ 5a‐d and 2‐phenylthio‐3‐bromofuropyridines 6a‐d with n ‐butyl‐, t ‐butyl‐ and methyllithium and lithioacetonitrile. Lithiation of compounds 1a‐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.