Amine-catalyzed direct Diels–Alder reactions of α,β-unsaturated ketones with nitro olefins

Direct Enantioselective Synthesis of Bicyclic Diels–Alder Products

“…[4] Asymmetric, organocatalytic methods for the generation of chiral dienes represent an attractive, but relatively undeveloped, alternative in the synthesis of enantioenriched cyclic systems. [5][6][7] In this context, Yamamoto and co-workers have developed an elegant organocatalytic, asymmetric pathway to the nitrosoDiels-Alder reaction. [6] Moreover, Barbas and coworkers published the first organocatalytic enaminepromoted Diels-Alder protocol between acyclic dienes and nitroolefins.…”

“…[6] Moreover, Barbas and coworkers published the first organocatalytic enaminepromoted Diels-Alder protocol between acyclic dienes and nitroolefins. [7] However, a moderate diastereoselectivity was achieved and only one example of modest asymmetric induction was reported. We recently found that proline and its derivatives catalyze one-pot three-component aza-Diels-Alder reactions between a,b-unsaturated cyclic ketones, anilines and formaldehyde that proceed via an asymmetric domino Mannich/aza-Michael pathway (Scheme 1).…”

Green approach using water mediated Diels-Alder reaction for the synthesis of some 2-(4-bromo-1-naphthyl)-3-(aryl) bicyclo[2.2.1]hept-5-ene methanones and evaluation of their antimicrobial and antioxidant activities

“…Chemists and scientists have paid much more attention to this environmentally benign water-mediated reaction for synthesizing methanones [3], cyclic imines [4], cyclohexanone derivatives [5,6], diones [7], peptide-oligonucleotide conjugates [8], aza compounds [9], bicyclic esters [10], anthracene derivatives [11], cyclic diacids [12], Michael adducts [13], cantharidine-like molecules [14] and melamine peptides [8]. The water mediated environmentally benign hetero Diels-Alder [4+2] cycloaddition reaction was 700 times faster than in nonaqueous phase [3].…”

“…The water mediated environmentally benign hetero Diels-Alder [4+2] cycloaddition reaction was 700 times faster than in nonaqueous phase [3]. Numerous catalysts were employed to perform this Diels-Alder reaction, such as specific and chiral Lewis acids [3,15], chiral bases [16], chiral amines [5,6], non-natural α-amino acids [17], bimodal catalysts [18], hydrogen bonding interactions [1], chiral silver phosphates [4], Ti(IV) compounds [19], alkaline salts [20], lithium perchlorate [10], pyridyl-modified RNA [11], fly-ash [21][22][23][24][25], carbocations [13], Cu(II) compounds [2], organo-tungstates with ionicliquids [26], ribozymes [27], low melting carbohydrates [28], and metal-free non-covalent compounds [29]. Fard et al have studied the solvent effect and performed DFT analysis of acid catalyzed Diels-Alder cycloaddition reaction of 2,5-dimethyl furan and maleic anhydride [30].…”

Exploiting the benefits of continuous-flow processing for the development of novel sustainable catalytic procedures

“…The revival of this chemistry is closely related with the discovery of the proline-catalyzed direct asymmetric intermolecular aldol reaction by List 113 and Diels-Alder reactions. 114 In such transformations, the function of the amine residue of proline is to activate the carbonyl compound by formation of an enamine for reaction with an electrophile, whereas, the carboxylic acid moiety coordinates the stereochemical outcome through hydrogen bonding (Scheme 8). 115,116 In the golden age of asymmetric catalysis, a wide array of new prolinederived organocatalysts were designed that offered improved catalytic activity and selectivity, and increased substrate scope.…”