Ring expansion: formal total synthesis of (−)-paroxetine

Cobalt carbonyl-catalyzed carbonylation of functionalized aziridines to versatile β-lactam building blocks

Aziridine to azetidin-2-one carbonylation as a convenient entry to pyrrolidines,C-fused bi- and tricyclic β-lactams and monocyclic carbapenem analogs.

Rapid Construction of (-)-Paroxetine and (-)-Femoxetine via N-Heterocyclic Carbene Catalyzed Homoenolate Addition to Nitroalkenes

A concise enantioselective synthesis of (-)-paroxetine (Paxil) and (-)-femoxetine has been achieved. Key to these syntheses is a N-heterocyclic carbene catalyzed homoenolate addition to a nitroalkene followed by in situ reduction of the nitro-group to rapidly access δ-lactams.

H12461. Fluorine as a Regiocontrol Element in the Ring Openings of Bicyclic Aziridiniums

The origin of the variation in the regioselectivity of the nucleophilic ring-opening of a series of bicyclic aziridinium ions derived from N-alkylprolinols was investigated by quantum chemical computations (M06-2X/6-31+G(d,p)-SMD). These aziridiniums differ only in the degree and the stereochemistry of fluoro substitution at C(4). With the azide ion as nucleophile, the ratio of the piperidine to the pyrrolidine product was computed. An electrostatic gauche effect influences the conformation of the adjoining five-membered ring in the fluorinated bicyclic aziridinium. This controls the regioselectivity of the aziridinium ring-opening.

Stereospecific construction of substituted piperidines. Synthesis of (−)-paroxetine and (+)-laccarin

Short and efficient enantioselective syntheses of (-)-paroxetine and (+)-laccarin are described based on the highly stereospecific cleavage of C(3)-substituted 1,3-cyclic sulfamidates.

Asymmetric hydrogenations for the synthesis of Boc-protected 4-alkylprolinols and prolines

The utility of 4-substituted prolinols and their corresponding prolines in peptides, peptidomimetics, and natural products has motivated researchers to find new and efficient routes for their preparation. Herein, we report a general approach to the synthesis of Boc-protected 4-alkylprolinols and prolines via a divergent asymmetric hydrogenation strategy. Intermediate exocyclic olefins were prepared by Wittig-type reactions with ketone 6 and subjected to hydroxyl and sterically directed reductions. The Crabtree catalyst (Ir[COD]PyPCy(3)PF(6)) proved to be highly effective in diastereoselective hydrogenations to give trans-substituted pyrrolidines (9). Good facial selectivities were also observed in heterogeneous hydrogenations with Raney-nickel to obtain cis-substituted pyrrolidines (11). Employing this strategy, we describe the synthesis of novel prolinol and proline-based building blocks for incorporation into biologically relevant peptidomimetics.