thiourea and acetylacetone

A series of 18 regio- and stereo-chemically diverse chiral non-racemic 1,2-, 1,3-, and 1,4-diamines have been synthesized from commercial (1

Topics: Bridged-Ring Compounds; Camphor; Catalysis; Diamines; Ketones; Models, Molecular; Molecular Structure; Nitro Compounds; Pentanones; Thiourea

An efficient method was developed to synthesize ferrocene-based bifunctional amine-thioureas bearing multiple hydrogen-bonding donors. Asymmetric Michael addition of acetylacetone to nitroolefins catalyzed by these novel bifunctional catalysts affords the Michael adducts in high yield and moderate to excellent enantioselectivities. Multiple hydrogen-bonds play an important role in accelerating the reaction.

Topics: Alkenes; Amines; Ferrous Compounds; Hydrogen Bonding; Metallocenes; Molecular Structure; Nitro Compounds; Pentanones; Stereoisomerism; Thiourea

New bifunctional organocatalysts amine-thioureas bearing multiple hydrogen bonding donors were synthesized and applied in catalytic asymmetric Michael addition of acetylacetone to aryl and alkyl nitroolefins. Multiple hydrogen bonding donors play a significant role in accelerating reactions, improving yields and enantioselectivities.

Topics: Alkenes; Amines; Catalysis; Hydrogen Bonding; Ketones; Molecular Structure; Nitro Compounds; Pentanones; Stereoisomerism; Thiourea

The mechanism of enantioselective Michael addition of acetylacetone to a nitroolefin catalyzed by a thiourea-based chiral bifunctional organocatalyst is investigated using density functional theory calculations. A systematic conformational analysis is presented for the catalyst, and it is shown that both substrates coordinate preferentially via bidentate hydrogen bonds. The deprotonation of the enol form of acetylacetone by the amine of the catalyst is found to occur easily, leading to an ion pair characterized by multiple H-bonds involving the thiourea unit as well. Two distinct reaction pathways are explored toward the formation of the Michael product that differ in the mode of electrophile activation. Both reaction channels are shown to be consistent with the notion of noncovalent organocatalysis in that the transition states leading to the Michael adduct are stabilized by extensive H-bonded networks. The comparison of the obtained energetics for the two pathways allows us to propose an alternative mechanistic rationale for asymmetric C-C bond forming reactions catalyzed by bifunctional thiourea derivatives. The origin of enantioselectivity in the investigated reaction is also discussed.

Topics: Alkenes; Catalysis; Crystallography, X-Ray; Ketones; Models, Molecular; Nitro Compounds; Pentanones; Stereoisomerism; Thermodynamics; Thiourea

[reaction: see text] A novel binaphthyl-derived amine thiourea organocatalyst has been developed and demonstrated to efficiently catalyze Michael addition reactions (using as low as 1 mol % loading) of diketones to nitroalkenes with remarkably high enantioselectivities.

Topics: Alkenes; Catalysis; Models, Molecular; Molecular Structure; Naphthalenes; Nitro Compounds; Pentanones; Stereoisomerism; Thiourea