نتایج جستجو برای: organocatalyst
تعداد نتایج: 407 فیلتر نتایج به سال:
In the title compound, C(19)H(21)NO(4), an organocatalyst with a tetra-hydro-isoquinoline backbone, the heterocyclic ring assumes a half-boat conformation. The dihedral angle between the aromatic rings is 82.93 (8)°. In the crystal, mol-ecules are linked via N-H⋯O and C-H⋯O hydrogen bonds, forming a layer parallel to (10[Formula: see text]).
A highly enantioselective Morita-Baylis-Hillman reaction of maleimides with isatin derived ketimines has been developed to obtain enantiomerically enriched 3-substituted-3-aminooxindoles using β-isocupreidine as an organocatalyst. Maleimide acting as a nucleophile provides products with up to 99% ee.
A chemo- and enantioselective cross-aza-benzoin reaction between enals and isatin-derived ketimines is disclosed. The high chemoselectivity (of the acyl anion reaction over enal α- and β-carbon reactions) is enabled by the electronic and steric properties of the N-heterocyclic carbene organocatalyst.
Enantioselective phosphination and hydrophosphonylation reactions between azomethine imines and diarylphosphine oxides or dialkyl phosphites were respectively developed by the use of a chiral squaramide as the hydrogen bonding organocatalyst, which afforded two types of phosphorus containing product in high yields with good to excellent enantioselectivities.
A cascade cyclization involving union of three imines by an organocatalyst proline is established to afford new fused-tetrahydroimidazo[1,5-c]imidazol-7-ones with excellent regio- and stereoselectivity. Another dehydrogenative cyclization by union of two imines is developed using the Cu(OTf)(2)-Ag(2)O combo catalyst to furnish functionalized imidazoles.
A highly active organocatalyst for alcohol oxidation has been developed. 9-Azanoradamantane N-oxyl (Nor-AZADO 4), constituting an unhindered, stable nitroxyl radical, exhibits superior catalytic activity to 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and AZADOs in the oxidation of alcohols to their corresponding carbonyl compounds.
Asymmetric intramolecular Michael reaction catalyzed by an organocatalyst derived from cysteine has been developed for the synthesis of chiral bicyclo[4.3.0]nonene and cis-disubstituted cyclopentane skeletons with a creation of three or two contiguous chiral centers in good yield with high diastereo- and excellent enantioselectivities.
The ring-opening polymerization of N-tosyl aziridines, in the presence of 1,3-bis(isopropyl)-4,5(dimethyl)imidazol-2-ylidene as an organocatalyst and an N-tosyl secondary amine as initiator mimicking the growing chain, provides the first metal-free route to well defined poly(aziridine)s (PAz) and related PAz-based block copolymers.
A variety of aldehydes and ketones were transformed to their corresponding cyanohydrin silyl ethers in good to excellent yields in the presence of 1-5 mol% of tris(2,4,6-trimethoxyphenyl)phosphine (TTMPP). Cyanohydrin carbonates were also readily prepared using 5-10 mol% of TTMPP as an organocatalyst.
The first Michael addition of 1,3-diaryl-1,3-propanedione to nitroolefins was demonstrated using a simple organocatalyst, which afforded excellent yields (81-97%) and enantioselectivities (90 to >99% ee); the catalyst and excess reactant can be reused seven times through a simple filtration operation.
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