نتایج جستجو برای: azomethine ylides
تعداد نتایج: 1359 فیلتر نتایج به سال:
1,3-Dipolar cycloadditions of isatins, benzylamine and benzylideneacetones were studied to prepare a series of novel spiropyrrolidine-oxindoles - 4'-acetyl-3',5'-diarylspiro[indoline-3,2'-pyrrolidin]-2-ones and 3'-acetyl-4',5'-diarylspiro[indoline-3,2'-pyrrolidine]-2-ones in good yields of up to 94% and with good regioselectivities. Regioselectivities are reversible by the addition of water or ...
The effect of substituents on the rate of conrotatory thermal cleavage of aziridine has been studied at the MP2(Full)/6-311++G(d,p)//MP2(Full)/6-31+G(d) level and also using SCS-MP2 methodology. While the parent compound has a high free energy of activation (194.6 kJ mol(-1)), this value could be drastically lowered by substituent effects. Anionic species were found to be particularly effective...
Lewis base catalysed 1,3-dipolar cycloaddition between α,β-unsaturated acyl fluorides and N-[(trimethylsilyl)methyl]amino ethers has been achieved using 1 mol% DMAP. Competition experiments and (19)F-NMR studies indicate that the cycloaddition occurs preferentially between the α,β-unsaturated acyl fluoride and the unstabilised azomethine ylide. In addition, an enantioselective variant, using ch...
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