Asymmetric synthesis of homoproline derivatives via Rh(I)-catalyzed hydrogenation using chiral bisphosphines as ligands

Stereoselective Synthesis of α-Disubstituted β-Homoprolines

An efficient enantioselective synthesis of chiral α-disubstituted β-homoprolines was developed, starting with the stereodivergent allylation of chiral N-tert-butanesulfinyl imines derived from 4-bromobutanal with indium or zinc and using well-established and reliable synthetic transformations. This methodology allows the easy introduction of different substituents at the α-position of the pyrrolidine scaffold and is characterized by the possibility of switching the absolute configuration of the newly formed stereocenter either by changing the configuration of the tert-butanesufinamide chiral auxiliary or by using a different stereodivergent allylation protocol with the same auxiliary.

Vibrational spectra, HOMO, LUMO, NBO, MEP analysis and molecular docking study of 2,2-diphenyl-4-(piperidin-1-yl)butanamide

The Fourier-Transform Infrared and Fourier-Transform Raman spectra of 2,2-diphenyl-4-(piperidin-1-yl)butanamide were recorded in the region 4000-400 cm(-1) and 4000-0 cm(-1). The vibrational wavenumbers are computed using HF and DFT methods. The complete vibrational assignments were performed on the basis of potential energy distribution using GAR2PED program. The geometrical parameters of the title compound are in agreement with the XRD data. From the MEP study, the negative electrostatic potential regions are mainly localized of carbonyl group and are possible sites for electrophilic attack and the positive regions are localized all the rings, indicating possible sites for nucleophilic attack. Stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using natural bond orbital analysis. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. PASS analysis of the title compound predicts among other activities, antidyskinetic activity. Molecular docking results draw us to the conclusion that the compound might exhibit inhibitory activity against adenosine A2A and may act as antidyskinetic agent.

Infrared spectrum, NBO, HOMO-LUMO, MEP and molecular docking studies (2E)-3-(3-nitrophenyl)-1-[4-piperidin-1-yl]prop-2-en-1-one

FT-IR spectrum of (2E)-3-(3-nitrophenyl)-1-[4-piperidin-1-yl]prop-2-en-1-one was recorded and analyzed. The vibrational wavenumbers were computed using HF and DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign IR bands. Potential energy distribution was done using GAR2PED software. The geometrical parameters of the title compound are in agreement with the XRD results. NBO analysis, HOMO-LUMO, first and second hyperpolarizability and molecular electrostatic potential results are also reported. The possible electrophile attacking sites of the title molecule is identified using MEP surface plot study. Molecular docking results predicted the anti-leishmanic activity for the compound.

Gold(I)-Catalyzed Intramolecular Hydroamination of N-Allylic,N'-Aryl Ureas to form Imidazolidin-2-ones

Treatment of N-allylic,N'-aryl ureas with a catalytic 1:1 mixture of di-tert-butyl-o-biphenylphoshphine gold(I) chloride and silver hexafluorophosphate (1 mol %) in chloroform at room temperature led to 5-exo hydroamination to form the corresponding imidazolidin-2-ones in excellent yield. In the case of N-allylic ureas that possessed an allylic alkyl, benzyloxymethyl, or acetoxymethyl substituent, gold(I)-catalyzed 5-exo hydroamination leads to formation of the corresponding trans-3,4-disubstituted imidazolidin-2-ones in excellent yield with ≥50:1 diastereoselectivity.

Improved protocol for asymmetric, intramolecular heteroatom Michael addition using organocatalysis: enantioselective syntheses of homoproline, pelletierine, and homopipecolic acid

An improved protocol for the construction of enantioenriched pyrrolidine, indoline, and piperidine rings using an organocatalyzed, intramolecular heteroatom Michael addition is described. Application to the enantioselective synthesis of homoproline, homopipecolic acid, and pelletierine has been accomplished.

Ir-catalyzed allylic amination/ring-closing metathesis: a new route to enantioselective synthesis of cyclic beta-amino alcohol derivatives

Ir-catalyzed allylic aminations of (E)-4-benzyloxy-2-butenyl methyl carbonate with benzylamine using Feringa's (Sa,Sc,Sc)-phosphoramidite as a chiral ligand afforded linear-aminated achiral product N,O-dibenzyl-4-amino-2-buten-1-ol regioselectively (linear/branched = >99/1), whereas the (E)-5-benzyloxy-2-pentenyl methyl carbonate showed completely opposite regioselectivity (linear/branched = >1/99) and afforded the optically active (3R)-N,O-dibenzylated 3-amino-1-penten-5-ol with very high enantioselectivity (96% ee), which was used as a key intermediate for the effective synthesis of various cyclic beta-amino alcohol derivatives through ring-closing metathesis in high yields.

Three-component synthesis of polysubstituted homoproline analogs

Tetrasubstituted pyrrolidines representing analogs of homoproline were synthesized by three-component condensation of aryl(heteroaryl)aldehydes, asparagine and N-methylmaleimide (NMM). Compounds with (1S*, 3R*, 3aS*, 6aR*)-configuration at the corresponding carbon positions of the bicyclic pyrrolidine ring could be isolated on a preparative scale.