H. Nakazumi, Shigeru Watanabe, T. Kitaguchi
Mar 1, 1990
Citations
0
Influential Citations
13
Citations
Journal
Bulletin of the Chemical Society of Japan
Abstract
The reaction of benzenethiol with ethyl benzoylacetate in polyphosphoric acid (PPA) at low temperature gave mainly ethyl 3-phenyl-3,3-bis(phenylthio)propionate 8 as an intermediate in the synthesis of thioflavones, while that from t-butylthiobenzene under similar conditions gave ethyl 3-(phenylthio)cinnamate 7 as a major product and many by-products. The reaction constant for intramolecular cyclic condensation of 7 in 98% sulfuric acid was −0.46 and −0.54 using Hammett substituent constants, σm and σm+, respectively. It is suggested that the increase of electron density at the ring closure site of the benzenethiol moiety of 7 promotes this ring closure reaction.