نتایج جستجو برای: imines
تعداد نتایج: 2655 فیلتر نتایج به سال:
A strategy for exo and enantioselective 1,3-dipolar cycloaddition of azomethine imines to 2-acryloyl-3-pyrazolidinone is described. The corresponding cycloadducts are isolated with high diastereoselectivities (up to >96:4 exo/endo) and enantioselectivities (up to 98% ee).
A method for the synthesis of α-amino acids by direct reductive carboxylation of aromatic imines with CO2 is described. The protocol employs readily available commercial reagents and serves as a one-step alternative to the Strecker synthesis.
Di-isobutylaluminum hydride and tri-iso-butylaluminum (DIBAL 1, TIBAL 2) are shown to be efficient hydrogenation catalysts for a variety of imines at 100 °C and 100 atm of H2, operating via a hydroalumination/hydrogenolysis mechanism.
The rsuiical cyclizations of N-aziridinyl imines and alkyl azides provided reliable methods for the formation of fiveand six-membered carbon-centered and nitrogen-centered radicals from acyclic precursors. NAziridinyl imino and azido groups were utilized as radical precursors as well as radical acceptors in radical cyclization. Furthermore, intramolecular addition of aminyl radicals to carbonyl...
The stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining TiCl4 or TiCl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. Subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...
thionyl chloride (or oxalyl chloride) has been used as an efficient and cheap acid activator for one-pot synthesis of β-lactams in good to excellent yields by reaction between imines and acids in the presence of triethylamine at room temperature.
Elucidation of mechanisms and discovery of novel reactions are interconnected, as four research chapters from the Munich laboratory demonstrate. 1) In a new opening of the furan ring, 2-methoxyfuran and tetra-acceptor-substituted ethylenes furnish methyl acrylates, which are cis-3-substituted by a cyclopropyl ring that bears the four acceptor groups. Experiments with trans- and cis-1,2-bis(trif...
The reactions of dimethoxycarbene (DMC; 2), which was generated in situ by thermal decomposition of 2,5-dihydro-2,2-dimethoxy-5,5-dimethyl-1,3,4-oxadiazole (1), with N-tosylated imines of xanthone and 2,3 : 6,7 dibenzosuberenone, 3a and 3d, respectively, led to different adducts with rearranged skeletons. In the case of 3a, the 1 :1 adduct 5 as well as the 2 : 1 adduct 6 were obtained (Scheme 2...
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