Enantioselective organocatalytic Michael additions of N,N′-dialkylbarbituric acids to enones

Abstract

N,N'-Dialkylbarbituric acids as cyclic malonamide donors were successfully used in the enantioselective Michael addition reaction of enones. Using cinchona alkaloid-based bifunctional squaramide as an organocatalyst, this Michael reaction of N,N'-di-tert-butylbarbituric acid with various enones features a highly enantioselective (91-99% ee) production of the corresponding optically active 5-substituted barbituric acid derivatives. The transformations of the Michael product for the barbituric acid structural unit were realized in two ways, deprotection to remove the N-tert-butyl group and alkylation to produce 5,5-disubstituted barbituric acid derivatives.

Thiosulfonates as Emerging Reactants: Synthesis and Applications

“…[236] Thee nantioselective addition in such ar eactionw as demonstrated by the group of Yang who employed ac hiral squaramide as efficient organocatalyst (route 3). [237] Thed esired 370 were obtained with high enantioselectivities of up to 89% ee.…”

Iodine and DMSO as Surrogate of Hazardous Metal and Non‐Metal Reagents in Organic Synthesis

“…Sulfidation of aromatic compounds via C−H activation to obtain biologically active species, [119–122] has gained significant attention [123–127] . However, there are only a handful of reports for sulfidation of perfluoroarenes; [128–132] in which the metal catalysts like palladium chloride (Scheme 11 (a)) [133] and high amounts of bases like KOH (Scheme 11 (c)) [134] have been used with diphenylsulphane to incorporate the sulphur containing fragment in the target motifs. All these methods have a limited substrate scope and some of them are incapable of producing unsymmetrical desired products.…”

PhNCO-enabled synthesis of secondary amides from N-(2-aminophenyl)benzamides

“…[10][11][12][13] These methods have proven effective for various amides; however, the reagents tend to be toxic and hard to separate, unrecoverable waste is produced and these methods fall short in terms of adhering to the principles of green chemistry. Lately, various nonclassical strategies have been developed, such as amidation of aldehydes, 14,15 amino carbonylation of alkynes, 16 and oxidation of alcohols with amines. 17 Although a large number of methods have been reported, transamidation reactions hold the potential to be the most useful class of reactions for the synthesis of secondary amides.…”