Stereoselective total synthesis of (±)-7-deoxy-trans-dihydronarciclasine, a potent antineoplastic phenanthridone alkaloid

A short and efficient stereoselective total synthesis of (+/-)-7-deoxy-trans-dihydronarciclasine, a highly potent antineoplastic agent and constituent of the Amaryllidaceae alkaloids, is described. Starting from a known arylcyclohexylamine-type precursor 6, the C-ring with the required stereochemistry is constructed using a chemo- and stereoselective enone reduction (NaBH4/CaCl2 system) and a Mitsunobu reaction. For the B-ring Closure, the Banwell modification of the Bischler-Napieralski reaction was applied. (C) 2009 Elsevier Ltd. All rights reserved.