Doubly stereocontrolled asymmetric conjugate addition of acetylacetone to nitroolefins catalyzed by bifunctional tertiary amine–thiourea catalysts derived from both acyclic α-amino acids and carbohydrates

Dianhydrohexitols: new tools for organocatalysis. Application in enantioselective Friedel-Crafts alkylation of indoles with nitroalkenes

“…[11][12][13][14] Although carbohydrate are very attractive starting material because of their availability and well defined stereocenters, only few thiourea organocatalysts derived from saccharide were used in asymmetric organocatalytic reactions, mainly for Mannich and aza-Henry reactions. [15][16][17][18] As a part of our ongoing program devoted to asymmetric catalysis, we were interested in the development of new chiral ligands derived from dianhydrohexitols (isomannide, isosorbide and isoidide). Ligands derived from dianhydroglycitols have already been used in organometallic catalysis to perform asymmetric Diels-Alder reactions, [19][20][21][22] nucleophilic addition to aldehyde, [23][24] hydrogen transfer reduction of prochiral ketones [25][26][27][28] and asymmetric hydrogenation of olefins.…”

Enantioselective and Regioselective Organocatalytic Conjugate Addition of Malonates to Nitroenynes

“…Interestingly, in our previous enantioselective Michael reactions between 1,3‐dicarbonyl compounds and nitroolefins,5ac two chiral elements of the catalyst 1a ( R A , S , S ) were found to be matched, whereas two chiral elements of the catalyst 1b ( R A , R , R ) were mismatched. The bifunctional thioureas 1c and 1d 5ad, ae developed by us recently provided product 4a in 67 % ee (entry 3) and −68 % ee (entry 4), respectively. Although Takemoto’s catalyst 1e ,5a which was an excellent catalyst in the Michael addition of malonates to nitroolefins, was evaluated, only 69 % ee was obtained in the current reaction (entry 5).…”

Highly efficient stereoconservative syntheses of new, bifunctional atropisomeric organocatalysts

“…1,2 The observed good stereocontrol achieved by the chiral bifunctional catalysts is due to concomitant and synergistic activation of both reacting partners during C-C bond formation.…”