Light in Aminocatalysis: The Asymmetric Intermolecular α‐Alkylation of Aldehydes

Following the light: Photoredox catalysis along with aminocatalysis have proved to be the right combination for one of the most challenging asymmetric transformation in organic synthesis: the direct intermolecular α‐alkylation of aldehydes.

     

Selective synthesis of α-trifluoromethyl-β-aryl enamines or vinylogous guanidinium salts by treatment of β-halo-β-trifluoromethylstyrenes with secondary amines under different conditions

Unprecedented selective reactions of β-halo-β-trifluoromethylstyrenes with secondary amines under different conditions were discovered. Depending on the electronic properties of the starting styrenes and the reaction parameters, two pathways were found. With neat secondary amines a series of α-trifluoromethyl-β-aryl enamines were prepared in high yields. In contrast, the reactions of the mentioned styrenes with the same amines in polar solvents by substitution of all halogen atoms gave vinylogous guanidinium salts. Possible reaction mechanisms are discussed.     

Reactions of 1,3,3,3-tetrafluoro-2-methoxycarbonylpropenesulfenyl chloride with enamines

1,3,3,3-Tetrafluoro-2-methoxycarbonylpropenesulfenyl chloride readily reacts with enamines (derivatives of -oxo acids) to give sulfenylation products. The reactions with N-aryl-substituted enamines are accompanied by cyclization to form N-aryl-2-(2,2,2-trifluoro-1-methoxycarbonylethylidene)-2,3-dihydrothiazoles.     

Palladium‐Catalyzed Intermolecular Oxidative Coupling Reactions of (Z)‐Enamines with Isocyanides through Selective β‐C(sp2)‐H and/or C=C Bond Cleavage

Herein, two efficient palladium‐catalyzed intermolecular oxidative coupling reactions of (Z)‐enamines with isocyanides via selective β‐C(sp²)‐H and/or C=C bond cleavage have been developed, leading to controllable chemodivergent and stereoselective construction of a wide range of (E)‐β‐carbamoylenamine derivatives containing strong intramolecular hydrogen bonds. Furthermore, possible reaction pathways for these transformations are proposed on the basis of preliminary mechanism studies.     

Chemistry of N,N-bis(silyloxy)enamines. 4. Study of the reactions of N,N-bis(silyloxy)enamines with 1,3-diones

Smooth C,C-cross-coupling of N,N-bis(silyloxy)enamines with methyl malonates gives the corresponding methyl -hydroxyiminoalkylmalonates.     

Structural sensitivity in phosphorylation of enamines—derivatives of β-aminocrotonic acid with diphenylchlorophosphine

The reaction of ‘push-pull’ enamines—derivatives of β-aminocrotonic acid with diphenylchlorophosphine has been investigated. Structural sensitivity of the reaction was found and is discussed.     

Synthesis and properties of the salts of 1-nitropropan-2-one and 1-nitrobutan-2-one

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Enamines of the 1,2,3,4-tetrahydroiso-quinoline series in the Chichibabin synthesis of pyrrolo[2,1-a]isoquinolines and in reaction with oxalyl chloride

It has been shown that the Chichibabin reaction of enamines of the 1,2,3,4-tetrahydroisoquinoline series and 1,2,3,4-tetrahydrobenzo[f]isoquinoline series with p-bromophenacyl bromide leads to pyrrolo[2,1-a]isoquinoline derivatives. The same heterocyclic system is obtained on interaction of 1-alkyl-3,4-dihydroisoquinolines or their benzo[f]-analogs with oxalyl chloride. The obtained dioxopyrrolines form derivatives of benzo[g]quinoxalino[2,3-b]indolizine on condensation with o-phenylenediamine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1068–1074, July, 2007.