Synthesis of Photochromic Monomers Derived from 1'-(2-Methacryloxyethyl)-3,3-Dimethyl-2- [2H] -Spirobenzopyran Indoline

摘要

The syntheses of five photochromic monomers derived from N-(2-metha-cryloxyethyl)-3',3'-dimethylspiro-[2H-l] benzopyrane-2,2'-indoline are reported.The preparation of these compounds involves the heterogeneous reaction between the N-(hydroxyethyl)-2,3,3-trimethylindolenonium bromide and methacryloyl chloride in a polar solvent.The esterificated salt is easily purified by crystallization in chloro-form-hexane.Further condensation with the proper 2-hydroxybenzaldehyde produces the photochromic monomer in high yield.This method can also be applied in the preparation of other spiropyrane derivatives.