Enantioselective synthesis and biological evaluation of a-hydroxylated lactone lignans

Abstract

A short and efficient synthesis of enantiomerically pure α-hydroxylated lactone lignans starting from commercially available diisopropyl malate is presented. Stereoselective alkylation with various benzyl bromides and saponification yielded the corresponding succinic acids. Acetalization afforded the dioxolanones, which were stereoselectively alkylated. Reduction (and deprotection, where required) yielded the lactone lignans in up to 30 % overall yield. The inhibition of the proliferation of HT29 colon cancer cells was investigated. One lignane, bis-2,4,6 trimethylbenzyllactone lignan, was active (IC50 = 35 μM), whereas all other tested lignans were inactive within the investigated concentration range.