Synthesis of a Benzolactone Collection using Click Chemistry

A collection of benzotriazoles consisting of seven compounds was prepared from the propynyl‐substituted benzolactone 1 and various azides using click chemistry. The lactone 1 was obtained through a short route by direct esterification of the allylbenzoic acid 9 with the alkynol 7 giving the benzoate 2 . The homopropargyl alcohol 7 in turn was obtained by opening the epoxide 6 with triisopropylsilyl acetylide. Ring‐closing metathesis of the ester 2 using Grubbs catalyst II followed by removal of the silicon protecting group furnished the lactone 1 . Two of the benzotriazoles, 17a and 17b , were also converted into the corresponding phenols to probe the role of the phenolic OH on the biological activity. All nine benzotriazoles showed cytotoxic activity in a L929 mouse fibroblast assay with IC 50 values in the low micromolar range. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)