A direct stereoselective approach to trans-2,3-disubstituted piperidines: application in the synthesis of 2-Epi-CP-99,994 and (+)-epilupinine.

A simple synthesis of enantiomerically pure piperidine esters is described, offering a straightforward access to the trans-2,3-disubstituted piperidine skeleton which is present in a broad range of biologically active compounds.

Diene-titanium complexes as synthetic intermediates for the construction of three- or five-membered carbocycles.

It has been shown that diene-titanium complexes exhibit substrate-dependent 1,2- or 1,4-dicarbanion reactivity. On this basis, 3-cyclopentenylamines and spiro-vinylcyclopropane lactams were easily prepared by using homoallylic Grignard reagents, Ti(O-i-Pr)4, and nitriles or cyanoesters, respectively.