Titanacyclopentene complexes and their application as 1,4-dicarbanion equivalents.

The treatment of Ti(OiPr)(4) with 3-butenylmagnesium chloride generates titanacyclopentene complexes which effectively add to carbonyl compounds and nitriles to afford the 1,4-coupling products with high Z:E selectivities.

A novel approach to prezizaane sesquiterpenes.

Prezizaane sesquiterpenes are an olfactorily interesting class of tricyclic natural products, which occur in some precious perfumery raw materials. These compounds are biosynthetically derived from farnesyl pyrophosphate via cyclization, but some questions regarding the stereoselectivity of this process have not yet been answered. We discuss a novel and concise access to the tricyclic framework of these sesquiterpenes, as exemplified by the synthesis of (+/-)-5-epi-sesquithuriferone (5-epi-4).