In this communication, a nitroso-ene cyclization was devised to rapidly construct 1-azaspiro[4.4]nonane, a key structural motif which was further implemented into the modular synthesis of (+/-)-cephalotaxine (6). The whole synthesis route to access the key intermediate 7 involves eight steps from a commercially available 1,2-epoxycyclopentane (12) and five purifications on silica gel column. The direct nitroso-ene reaction to 1-azabicyclo[4.4]non-2-one paves a way to a future development of the practical synthesis of cephalotaxus alkaloids. (C) 2015 Published by Elsevier Ltd.
Huang SH,Tian XC,Mi XW,et al. Nitroso-ene cyclization enabled access to 1-azaspiro[4.4]nonane and its application in a modular synthesis toward (+/-)-cephalotaxine[J]. Tetrahedron Lett.,2015,56(48):6656-6658.