This study was aimed at the synthesis of fused benzothiophene derivatives containing heterocyclic moiety. The reaction of the tetrahydrobenzo[b]thiophene derivatives 1a,b with ethoxycarbonylisothiocyanate afforded the thiourea derivatives 2a,b. Cyclization of the latter products gave the annulated benzo[b]thienopyrimidine derivatives 3a,b. Compounds 2a,b and 3a underwent a series of heterocycli...

Successful alkylations of the nitrogen of ethyl indol-2-carboxylate were carried out using aq. KOH in acetone. The respective N-alkylated acids could be obtained without separating the N-alkylated esters by increasing the amount of KOH and water. The use of NaOMe in methanol led to transesterification instead of the alkylation, while the use of NaOEt led to low yields of the N-alkylated acids. ...

A small-ring phosphacycle, 1,2,2,3,4,4-hexamethylphosphetane, is found to catalyze deoxygenative N-N bond-forming Cadogan heterocyclization of o-nitrobenzaldimines, o-nitroazobenzenes, and related substrates in the presence of hydrosilane terminal reductant. The reaction provides a chemoselective catalytic synthesis of 2H-indazoles, 2H-benzotriazoles, and related fused heterocyclic systems with...