Facile construction of the lathyrane-type framework via Cr–Ni-mediated cyclization as a key step

A tricyclic compound (1) that has a lathyrane-type framework was designed as a model compound of the key intermediate of some diterpenes from Euphorbiacea and Thymeleacea. Two fragments 2 and 3 were derived from commercially available methyl cyclopentanone-2-carboxylate and (+)-3-carene, respectively. These fragments were coupled by a Cr(II)–Ni(II)-mediated reaction, followed by cyclization under the same conditions to afford 1 in moderate yield.