Ultrasound promoted synthesis of thioesters from 2-mercaptobenzoxa(thia)zoles
作者:Anaí Duarte、Wilson Cunico、Claudio M.P. Pereira、Alex F.C. Flores、Rogério A. Freitag、Geonir M. Siqueira
DOI:10.1016/j.ultsonch.2009.08.004
日期:2010.2
An ultrasound-enhanced method has been developed for the synthesis of a variety of thioesters from benzoyl chlorides and 2-mercaptobenzoxa(thia)zoles. Applying this methodology, 14 compounds were synthesized in excellent yields. (C) 2009 Elsevier B.V. All rights reserved.
Refractive Index Changes in Polymers Bearing Pendant Active Ester Groups by Thermal Rearrangement Reaction
Linear and branched polymers bearing S-(2-benzoxazolyl) thioester groups were selectively synthesized by free radical and photoinitiated radical polymerization, respectively, of S-(2-benzoxazolyl)-4-vinylthiobenzoate. Upon heating, the pendant S-(2-benzoxazolyl) thioester groups were converted to 3-acylbenzoxazoline-2-thione groups, accompanied with a change of refractive index (Δn) of about +0.01 in both cases. The structural conversion was confirmed by UV–vis and IR spectroscopy, as well as comparison with authentic polymers bearing 3-acylbenzoxazoline-2-thione groups (similarly synthesized from 3-(4-vinylbenzoyl)benzoxazoline-2-thione). Application of such thermally induced rearrangement reactions may provide a new approach for obtaining materials whose refractive index can be changed by heat (e.g., generated by a laser beam).