نتایج جستجو برای: mannich type reaction
تعداد نتایج: 1700335 فیلتر نتایج به سال:
The title compound, characterized by X-ray crystallography, was accessed in 4 steps with 92 % ee. and 25 yield from an O-protected (R)-BINOL precursor. This revised synthetic route relied on a chlorosulfonylation reaction, as shortcut to previously developed sequence requiring the use of toxic SO2 gas bromine. strongly electron-impoverished (R)-6,6′-Tf2-BINOL proved effective ligand metal-catal...
Cyclic tetrapeptide and depsipeptide natural products have proven useful as biological probes and drug candidates due to their potent activities as histone deacetylase (HDAC) inhibitors. Here, we present the syntheses of a class of cyclic tetrapeptide HDAC inhibitors, the azumamides, by a concise route in which the key step in preparation of the noncanonical disubstituted β-amino acid building ...
Chiral C3-symmetric trisoxazolines are highly efficient stereodirecting ligands in enantioselective Cu(II) Lewis acid catalysis which is based on the concept of a stereoelectronic hemilability of the divalent copper; in direct comparison with the analogous bisoxazoline systems they are more efficient in the enantioselective alpha-amination as well as the enantioselective Mannich reaction of pro...
An NHC-catalyzed regio- and stereoselective Mannich/lactamization domino reaction of N-(benzothiazolyl)imines with α-chloroaldehydes has been developed. This new protocol provides a facile approach for the asymmetric synthesis of benzothiazolo-pyrimidinones and a pyrrolo[1,2-a]indolone in moderate to good yields (34-78%) and excellent stereoselectivities (87-99% ee, up to >20 : 1 d.r.).
An enantio- and diastereoselective direct vinylogous Mannich reaction of alpha,alpha-dicyanoolefins and N-sulfonyl alkylimines has been developed by the catalysis of a new family of bifunctional organocatalysts merging chiral BINOL and 9-amino-9-deoxyepi-cinchona alkaloid skeletons, from which chiral beta-, delta- or gamma-amino compounds could be efficiently derived.
A direct asymmetric Mannich reaction of N-unprotected 3-bromooxindoles with N-Ts-imines catalyzed by bifunctional thiourea derived from 2-substituted cinchona alkaloid was developed. Products with vicinal chiral tertiary and brominated quaternary stereogenic centers were achieved in excellent diastereo- and enantioselectivity (up to 99 : 1 dr, 99% ee).
Total syntheses of the potent neurotoxins, environmental hazards, and biochemical probes anatoxin-a and homoanatoxin have been achieved from a common intermediate using a combined two-directional synthesis-tandem reaction strategy which includes key advances in oxidative desymmetrisation, tandem Michael-intramolecular Mannich cyclisations and a new method for deprotection of N-tosyl anatoxin-a.
The multicomponent synthesis of α,β-disubstituted N-sulfonyl β-amino esters is described. It involves a zinc-mediated, cobalt-catalyzed three-component reaction between sulfonylimines, acrylates and organic bromides. A possible mechanism is proposed, emphasizing the intermediate formation of an organocobalt as the initiator of a Mannich-like process.
The synthesis of (diarylmethyl)sulfonamides and related compounds by a new manganese-mediated, cobalt-catalyzed three-component reaction between sulfonamides, carbonyl compounds and organic bromides is described. This organometallic Mannich-like process allows the formation of the coupling products within minutes at room temperature. A possible mechanism, emphasizing the crucial role of mangane...
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