One-pot synthesis of new liquid crystalline indeno heterocyclic materials

Abstract

Disulfur dichloride converts 1-(dicyanomethylene)indane 3 into the methyleneindene 4 and the red indeno-1,2-thiazine 5; it also converts inden-3-ylacetic acid 7 into methyleneindenes 8 and 9, dithiolone 10 and the deep purple thiophenone 11; upon melting crystals of 4 and 11 are strongly birefringent and 5 exhibits thermochromicity; mechanisms are outlined for the novel transformations and X-ray crystal structures for 5 and 10 are analysed.