Process for preparing 4,4-dialkyl-6-halo-chromans or thiochromans useful as pharmaceutical intermediates

摘要

A process of preparing intermediates useful in making compounds with retinoic acid-like activity is disclosed. The intermediates are halogenated chromans and thiochromans of the formula shown below and are prepared by the alkylation of a phenol or thiophenol with an alkene compound (the starting materials shown in the formula below), cyclization and halogenation. <IMAGE> +TR <IMAGE> In the formula the symbols have the following meanings: R1 and R2 are C1 to C4 alkyl, R3 is H or C1 to C4 alkyl, X is oxygen or sulfur, Y is a leaving group, and Z is chlorine, bromine or iodine.