Selective reductions of cyclic 1,3-diesters by using SmI(2) and H(2)O.

SmI(2)/H(2)O reduces cyclic 1,3-diesters to 3-hydroxyacids with no over reduction. Furthermore, the reagent system is selective for cyclic 1,3-diesters over acyclic 1,3-diesters, and esters. Radicals formed by one-electron reduction of the ester carbonyl group have been exploited in intramolecular additions to alkenes.

Selective reductions of cyclic 1,3-diesters using SmI(2) and H(2)O.

SmI(2)-H(2)O reduces cyclic 1,3-diesters to 3-hydroxyacids with no over-reduction. Furthermore, the reagent system is selective for cyclic 1,3-diesters over acyclic 1,3-diesters and esters. Experimental and computational studies suggest that the origin of the selectivity lies in the initial electron transfer to the ester carbonyl and the anomeric stabilization of the resulting radical-anion intermediate.

A Samarium(II)-mediated, stereoselective cyclization for the synthesis of azaspirocycles.

Unsaturated keto-lactams undergo sequential conjugate reduction-aldol cyclization on treatment with SmI 2 to give syn-spirocyclic pyrrolidinones and piperidinones containing vicinal, fully substituted stereocenters with complete diastereocontrol. The substituent on nitrogen and the lactam ring size have a marked impact on the efficiency of the spirocyclization.

Synthesis of (-)-Indolizidine 167B based on domino hydroformylation/cyclization reactions.

The synthesis of (-)-Indolizidine 167B has been achieved from optically active (R)-3-(pyrrol-1-yl)hex-1-ene. The key step is a highly regioselective hydroformylation reaction and a one-pot intramolecular cyclization providing a general approach to the indolizine nucleus.