RESUMO
Various multisubstituted piperidines containing a phenyl group at C-2 can be opened regio- and stereoselectively with cyanogen bromide. The ring-opened products contain useful cyanamide and benzylic bromide functional groups. The benzyl bromide can be cleanly reduced, or substituted with various nucleophiles via an S(N)2 process to add additional heteroatoms stereoselectively. This methodology is useful for the stereoselective synthesis of uniquely substituted alkylamine derivatives containing multiple chiral centers and various functionality. Diastereomerically pure amino alcohols containing three to five contiguous stereocenters were prepared using this strategy.
Assuntos
Amino Álcoois/química , Amino Álcoois/síntese química , Catálise , Brometo de Cianogênio/química , Hidrogenação , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Modelos Moleculares , Conformação Molecular , Piperidinas/química , Espectrofotometria Infravermelho , EstereoisomerismoRESUMO
Multisubstituted piperidines containing a phenyl group at C-2 can be opened regio- and stereoselectively with cyanogen bromide. The ring-opened products contain useful cyanamide and benzylic bromide functional groups. This methodology is useful for the stereoselective synthesis of uniquely substituted alkylamine derivatives containing multiple chiral centers and various functionality.
Assuntos
Amino Álcoois/síntese química , Piperidinas/química , Compostos de Benzil/química , Cianamida/química , Brometo de Cianogênio/química , Ciclização , EstereoisomerismoRESUMO
During a study on iodocyclocarbamation reactions of 2-styryl-4-piperidones, a novel ring contraction was observed. Iodocyclocarbamation of 2-styryl-4-piperidone 3 gave the bicyclic carbamate 4. Reduction of 4 under free-radical conditions effected a stereoselective ring contraction to provide oxazolidinone 6. A three-electron-three-center mechanism is proposed.
