نتایج جستجو برای: phosphorus ylide
تعداد نتایج: 41924 فیلتر نتایج به سال:
An efficient diastereoselective rhodium catalyzed synthesis of indolines possessing two contiguous tetrasubstituted carbon centers has been achieved with good to excellent yields using ortho-vinylanilines and iminocarbenes derived from N-sulfonyl-1,2,3-triazoles. The reaction affords excellent cisdiastereoselectivity through the initial formation of a N-ylide followed by intramolecular trapping...
The 3+2 cycloaddition reaction of 1-(4-phenylphenacyl)-1,10-phenanthrolinium ylide 4 with activated alkynes gave pyrrolo[1,2- 4a][1,10]phenanthrolines 6a-d. The "one pot" synthesis of 6a,b,d from 4, activated alkenes, Et(3)N and tetrakis-pyridine cobalt (II) dichromate (TPCD) is described. The helical chirality of pyrrolophenanthrolines 6b-d was put in evidence by NMR spectroscopy.
A highly stereoselective [2,3]-sigmatropic rearrangement of sulfur ylide generated through Cu(I) carbene and allyl and propargyl sulfides by a double asymmetric induction approach that combines a chiral camphor sultam auxiliary and Cu(I) catalyst with chiral or achiral diimine ligands has been developed.
Carbene catalysed redox activation of α,β-unsaturated aldehydes is applied for generation of α,β-unsaturated acyl azoliums which undergo cyclopropanation upon reaction with a sulfur ylide and an alcohol to give the corresponding cyclopropanecarboxylic acid esters. With chiral carbenes good to excellent diastereo and enantioselectivities are obtained.
tert-Butyl cinnamates are aziridinated with high trans-selectivity by an N-N ylide generated in situ from N-methylmorpholine and O-diphenylphosphinyl hydroxylamine. The resulting N-unfunctionalised aziridines are shown to be versatile synthetic building blocks that undergo highly selective ring-opening reactions with a wide range of nucleophiles.
A convergent, nine-step (LLS), enantioselective synthesis of α-cyclopiazonic acid and related natural products is reported. The route features a) an enantioselective aziridination of an imine with a chiral sulfur ylide; b) a bioinspired (3+2)-cycloaddition of the aziridine onto an alkene; and c) installation of the acetyltetramic acid by an unprecedented tandem carbonylative lactamization/N-O c...
Carbonyl ylides are generally non-isolable reactive intermediates and have been extensively utilized as the dipole in 1,3-dipolar cycloaddition reactions with electron-deficient and electron-rich dipolarophiles to afford polycyclic compounds including five-membered oxacycles. The most efficient method for generating the carbonyl ylide is the interaction of a metal carbene complex with the oxyge...
The first examples of azomethine ylides derived from allylic amine and glyoxal precursors are reported. The condensation of primary allylic and α-aryl amines with glyoxylates or α-aryl glyoxals affords conjugated azomethine ylides that undergo facile [3 + 2] cycloaddition, providing 5-alkenyl pyrrolidine cycloadducts that cannot be accessed through the classical use of amino esters as ylide pre...
Trifluoromethylsulfinyl and trifluoromethylthio groups are both important substituents for pharmaceuticals, agrochemicals and functional materials. We herein report the trifluoromethylthiolation of allyl alcohols 2 with trifluoromethanesulfonyl hypervalent iodonium ylide 1 under copper catalysis to provide trifluoromethylsulfinyl compounds 3. Trifluoromethylthiolation of boronic acids 4 with 1 ...
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