Synthesis of novel thermally reversible photochromic axially chiral spirooxazines.

The Suzuki reactions of diboronic acid 1 and bromo-spirooxazine 2, under N(2) atmosphere and aerobic conditions, gave the dispirooxazine-substituted binaphthyl product 3 and the monospirooxazine-substituted binaphthyl derivative 4, respectively. The thermally reversible photochromic behavior of the target axially chiral spirooxazines 3 was investigated, and both the ring-opening process upon irradiation with 365 nm light and the thermally reverse ring-closing process were fast. These chiral spirooxazines were found to impart their chirality to an achiral liquid crystal host, at low doping levels, to form a self-organized photoresponsive helical superstructure.