Enantioselective Organocatalytic Enamine C−H Oxidation/Diels‐ Alder Reaction

Abstract

-unsaturated aldehydes have been traditionally used in LUMO lowering asymmetric aminocatalysis (iminium catalysis), while the use of saturated aldehydes as substrates in this type of catalysis has been elusive, until recently. Herein, we demonstrate that organic, single-electron oxidants in the presence of diarylprolinol silylether type catalysts serve as effective tools for the transformation of electron rich enamines to iminium ions which partake in a subsequent Diels-Alder reaction. This enantioselective one-pot transformation represents the first example of saturated aldehydes being used in domino Diels-Alder reaction processes and demonstrates the power of this protocol for construction of stereo-defined chiral compounds and building blocks.

Organo‐Cascade Catalysis: Application of Merged Iminium‐Enamine Activation Technique and Related Cascade Reactivities

“…Chen's group developed this nice reaction pathway via this unique triple-Michael/aldol process (Scheme 6). [44] This quadruple catalysis may also be employed with using other types of electrophiles, such as niroolefins (24) and cinnamaldehyde to produce derivatives of spirooxindoles (25) as shown in (Scheme 6).…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] Structural diversity with molecular level reactivity of chemical compounds has enthralled synthetic chemists during last couple of decades. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Organocatalytic transformation of small organic molecules remains a central paradigm and widely employed chemical strategy for the development of organic chemistry as well as chemical sciences. While the synthetic approaches have been conventionally focused upon to achieve molecular complexity, however catalytic cascade reactions have been experienced a considerable attraction for making a valuable effort to reduce time with increase of efficiency for conventional synthetic methods.…”

“…In the advancement of different organocatalytic cascade reactions, [5] enamine catalysis opens up new opportunities in improvising the transformations of small molecules that enlighten up to synthesis smart functional materials of unique properties. [17,19,21,22,24,[27][28][29][30] The name "enamine" was first coined by Witting in 1927. [32] The earliest example of enamine catalysis was reported by Lindwall and group by reporting a reaction between isatin and ketones.…”

“…Therefore, synthetic organic chemists exhibit an escalating demand in iminiumenamine catalysed cascade reactions. [22][23][24][25][26][27][28][29][30] It has been well documented that atom economy, step economy and the scope of highly efficient catalytic reactions having high stereo-control (enantioselective and diastereoselctive) properties are integrally associated with enamine-iminium catalyzed reactions. The use of HOMO-raising enamine activation with LUMO-lowering iminium ion activation has been extensively utilizing by synthetic organic chemists over the years.…”

Theoretical Study of Diels-Alder Reaction of But-3-en-2-one with Hexa-1,2,4-triene: A Density Functional Theory Study

“…Diels-Alder cycloaddition is one of the most significant and useful tools available in synthetic chemistry (Kal-Koshvandi and Heravi, 2019). This organic reaction is widely used to build six-member rings with a maximum of four stereogenic centers on a regal and stereo-controlled route (Džambaski, et al, 2019;Zhang, et al, 2019). with the potential formation of carbon-carbon, carbon-heteroatom, and heteroatom-heteroatom bonds (Baeza, 2018;Boger and Weinreb, 2012;Siah, Leung and Mok, 1995).…”