0000000001046475
AUTHOR
Ignacio De Alfonso Marzal
Diastereoselective synthesis of antiquorin and related polyoxygenated atisene-type diterpenes
Abstract A diastereoselective approach to polyoxygenated atisene-type diterpenes starting from (S)-(+)-carvone is described. The key steps used in the preparation of the atisene framework are an intramolecular Diels–Alder reaction, an intramolecular diazoketone cyclopropanation, an endocyclic cyclopropane ring cleavage and the regioselective reduction of an allylic bromide by a low-valent chromium species. The synthesis of natural atisanes antiquorin (1), atis-16-ene-3,14-dione (3), atis-16-ene-2,3,14-trione (8) and 3β-hydroxy-atis-16-ene-2,14-dione (9) following this approach is presented. Also described is the synthesis of 18-hydroxy-atis-16-ene-3,14-dione (5), the structure erroneously a…
A unified synthetic approach to trachylobane-, beyerane-, atisane- and kaurane-type diterpenes
A general synthetic approach to the polycyclic carbon skeleton of biogenetically related trachylobane, beyerane, atisane, and kaurane diterpenes from carvone is described. The skeleton of these diterpenes is prepared from a common intermediate, that is, 25, readily prepared from carvone using an IMDA reaction and an intramolecular diazo ketone cyclopropanation of an unsaturated ketone as key steps. The tetracyclic diterpene ring systems are obtained from this key trachylobane-type intermediate through the regioselective reductive cleavage of the cyclopropane ring, after adequate modification of the functionalization around the tricyclo[3.2.1.02,7]octane moiety.
CCDC 626412: Experimental Crystal Structure Determination
Related Article: Antonio Abad, Consuelo Agulló, Ana C. Cuñat, Ignacio de Alfonso Marzal, Antonio Gris, Ismael Navarro, Carmen Ramírez de Arellano|2007|Tetrahedron|63|1664|doi:10.1016/j.tet.2006.11.083