potentially useful chirons for synthesis of terpenes such as drimanes, labdanes and triterpenes. The stereoselectivity of the second alkylation step which determines the stereochemistry of the ring junction has been studied and the results explained by the model of Tomioka. Several types of products may be formed depending on the acid used and a rearrangement has been observed in one case.
Two regiospecific consecutive alkylations of carvone at C4 followed by acid-catalysed cyclisation afford bicyclic ketones which are potential intermediates for the synthesis of several classes of terpenes. Depending on the sequence of alkylation trans fused ketone or a mixture of and cis fused ketone may be prepared in only three steps, thus constituting a new type of annulation of carvone.
Synthesis of Terpenoid Unsaturated 1,4-Dialdehydes. π-Facial Selectivity in the Diels−Alder Reaction of the 1-Vinyl-2-methylcyclohexene Moiety of Polycyclic Systems with DMAD
作者:Antonio Abad、Consuelo Agulló、Lourdes Castelblanque、Ana C. Cuñat、Ismael Navarro、M. Carmen Ramírez de Arellano