Facile synthetic route to enantiopure unsymmetriccis-2,5-disubstituted pyrrolidines

Diastereoselective C-H Bond Amination for Disubstituted Pyrrolidines

We report herein the improved diastereoselective synthesis of 2,5-disubstituted pyrrolidines from aliphatic azides. Experimental and theoretical studies of the C-H amination reaction mediated by the iron dipyrrinato complex (Ad L)FeCl(OEt2 ) provided a model for diastereoinduction and allowed for systematic variation of the catalyst to enhance selectivity. Among the iron alkoxide and aryloxide catalysts evaluated, the iron phenoxide complex exhibited superior performance towards the generation of syn 2,5-disubstituted pyrrolidines with high diastereoselectivity.

Facile access to unnatural dipeptide-alcohols based on cis-2,5-disubstituted pyrrolidines

Well-defined unnatural dipeptide-alcohols based on a cis-2,5-disubstitued pyrrolidine backbone were synthesized from commercially available starting materials meso-diethyl-2,5-dibromoadipate, (S)-(−)-1-phenylethylamine, and phenylalaninol. The structures of these unnatural dipeptide-alcohols are supported by HRMS, ¹H- and ¹³C-NMR spectroscopy. These unnatural dipeptide-alcohols can act as building blocks for peptidomimetics.

One-pot tandem cyclization of enantiopure asymmetric cis-2,5-disubstituted pyrrolidines: Facile access to chiral 10-heteroazatriquinanes

A series of chiral 10-heteroazatriquinanes were synthesized from enantiopure asymmetric cis-2,5-disubstituted pyrrolidines through a one-pot tandem cyclization procedure. The structures and configurations of these new chiral 10-heteroazatriquinanes are confirmed by X-ray single-crystal diffraction analysis.

Stereoselective synthesis of cis-2,5-disubstituted pyrrolidines via Wacker-type aerobic oxidative cyclization of alkenes with tert-butanesulfinamide nucleophiles

Palladium(II)-catalyzed aerobic oxidative cyclization of alkenes with tethered tert-butanesulfinamides furnishes enantiopure 2,5-disubstituted pyrrolidines, originating from readily available and easily diversified starting materials. These reactions are the first reported examples of metal-catalyzed addition of sulfinamide nucleophiles to alkenes.

Exploiting the ring strain in bicyclo[2.2.1]heptane systems for the stereoselective preparation of highly functionalized cyclopentene, dihydrofuran, pyrroline, and pyrrolidine scaffolds

The high strain of bicyclic systems drives retro-condensation reactions on bridgehead substituted bicyclo[2.2.1]hept-2-enes giving rise to orthogonally functionalized cyclopentene, 2,5-dihydrofuran, and 3-pyrroline scaffolds. Retro-Dieckman reactions were easily carried out on 3-tosyl-(7-carba/7-oxa/7-aza)bicyclo[2.2.1]hept-5-en-2-ones. Retro-aldol reactions of N-Boc-3-tosyl-7-azabicyclo[2.2.1]hept-5-en-2-ol and functionalized N-Boc-3-tosyl-7-azabicyclo[2.2.1]heptan-2-ols yield functionalized pyrrolidine scaffolds stereoselectively. The same reaction does not work with corresponding norbornene and 7-oxanorbornene derivatives.

Conversion of α-amino acids into bioactive o-aminoalkyl resorcylates and related dihydroxyisoindolinones

The synthesis of biologically active o-aminoalkyl resorcylates and related dihydroxyisoindolinones from functionalized α-amino acids without the use of phenolic protection is described. The key aminoalkyl-diketo-dioxinone intermediates were prepared utilizing a crossed Claisen condensation reaction in the presence of diethylzinc. The aromatic unit was constructed via late stage cyclization and aromatization, and subsequent modification provided the novel resorcylates which showed activity against a selection of receptors and kinases, including 5-HT and CDK.