Stereocontrolled synthesis of polysubstituted piperidines from vinylogous Mannich adducts and aldehydes

Condensation of readily available 5-(aminoalkyl)furan-2-ones, derived from the Mannich-type reaction between 2-silyloxyfurans and acyliminium ions, with an α-unsubstituted aliphatic aldehyde leads to substituted 1,2,3,4-tetrahydropyridines in a process involving an enamine conjugate addition. Reduction of the tetrahydropyridine double bond then affords 3,4,5-tri- or 3,4,5,6-tetra-substituted piperidines stereoselectively.     

Pd-mediated synthesis of 2-arylquinolines and tetrahydropyridines from modified Baylis-Hillman adducts

We synthesized 2-arylquinolines and tetrahydropyridines via palladium-mediated Heck type reactions starting from the Baylis-Hillman adducts. 2-Arylquinolines were prepared via the Heck type cyclization followed by concomitant aerobic oxidation.     

Facile domino reactions in the statistically controlled product- and stereoselective synthesis of densely functionalized cis-1,4-cyclohexa-1,4-dienes and trans,trans-trisubstituted-1,2,5,6-tetrahydropyridines

The domino reactions of ethyl 3-oxo-4-(arylsulfonyl)butanoates with aromatic aldehydes in a 2:1 molar ratio in the presence of a catalytic amount of ammonium acetate furnished densely functionalized cyclohexa-1,4-dienes stereoselectively, while the domino reactions of ethyl 3-oxo-4-(arylsulfonyl)butanoates, aromatic aldehydes, and ammonium acetate in a 1:2:2 molar ratio afforded highly functionalized 1,2,5,6-tetrahydropyridines stereoselectively.     

Stereoselective Synthesis of 2,6‐Disubstituted Tetrahydropyridines Via Aza‐Diels‐Alder Reactions

Abstract

The aza‐Diels‐Alder reactions of (E)‐2‐(phenylthio)‐1,3‐pentadiene (2) with iminium salts gave the 2,6‐disubstituted tetrahydropyridines 3–8. Factors influencing the stereochemistry and reactivity of these reactions were also studied.     

α-Trifluoromethyl-β-aryl enamines in the synthesis of trifluoromethylated heterocycles by the Fischer and the Pictet-Spengler reactions

α-Trifluoromethyl-β-aryl enamines were successfully used as synthetic equivalents of benzyltrifluoromethyl ketones in both the Fischer indole synthesis and the Pictet-Spengler reaction. Accordingly, 2-trifluoromethyl indoles and a variety of trifluoromethylated 4,5,6,7-terahydro-1H-pyridines including carbolines were synthesized in moderate to good yields.     

Ceric ammonium nitrate (CAN) catalyzed synthesis and α-glucosidase activity of some novel tetrahydropyridine phosphonate derivatives

Abstract

A simple and highly efficient multicomponent one-pot synthesis of a series of pharmaceutically interesting functionalized tetrahydropyridine phosphonate derivatives has been developed based on low-cost and environmentally benign ceric ammonium nitrate (CAN) catalyst via tandem reactions of 1,3-dicarbonyl compounds, diethylphosphoramidate and various aromatic aldehydes in acetonitrile at room temperature. High atom economy, good yields, eco-friendliness and mild reaction conditions are some of the important features of this protocol.     

Lactones from lactones: regio and diastereoselective double dinucleophilic additions of bis(OTMS) ketene acetals to pyridines

Lactones from lactones: a cascade transformation is observed during two successive double nucleophilic additions of bis (TMS) ketene acetals to pyridines.     

An enantioselective organocatalyzed aza-MBH domino process: application to the facile synthesis of tetrahydropyridines

A chiral acid-base organocatalyst was found to promote an aza-MBH domino process between α,β-unsaturated carbonyl compounds and N-tosylimines to afford tetrahydropyridine derivatives with high enantioselectivity.     

Cyanuric chloride catalyzed metal-free mild protocol for the synthesis of highly functionalized tetrahydropyridines

An environmentally benign, facile and elegant synthetic approach for the convenient access of a series of diverse 2,6-diaryl-tetrahydropyridine-3-carboxylates via a one-pot, pseudo five-component condensation of ethyl acetoacetate, anilines and aromatic aldehydes under mild reaction conditions has been described. This domino strategy allows rapid cyclization in the presence of 10 mol% of cyanuric chloride as a source of hydrochloric acid to afford the desired target skeletons in excellent yields. The present protocol offers prominent advantages of simple operational procedure, metal-free organocatalyst, practically robust and extensive substrate scope.     

Synthesis of poly-substituted tetrahydropyridines from Baylis-Hillman adducts modified with N-allylamino group via radical cyclization

An expedient method was developed for the synthesis of 1,4,5,6-tetrahydropyridines by radical cyclization protocol involving consecutive 1,5-hydrogen transfer and double bond isomerization process starting from Baylis-Hillman adducts.