Synthesis of prolines by enantioselective 1,3-dipolar cycloaddition of azomethine ylides and alkenes catalyzed by chiral phosphoramidite-silver(I) complexes
The endo-diastereo- and enantioselective 1,3-dipolar cyclo-addition of azomethine ylides and electrophilic alkenes is ef-ficiently catalysed by chiral phosphoramidite-silver(I) Per-chlorate complexes. The reaction allows the presence of dif-ferent types o
Najera, Carmen,De Retamosa, Maria Gracia,Martin-Rodriguez, Maria,Sansano, Jose M.,De Cozar, Abel,Cossio, Fernando P.
experimental part
p. 5622 - 5634
(2010/03/01)
Enantioselective synthesis of polysubstituted prolines by Binap-silver-catalyzed 1,3-dipolar cycloadditions
The enantioselective 1,3-dipolar cycloaddition reaction of stabilized azomethine ylides, generated from iminoesters, with maleimides was efficiently achieved by intermediacy of an equimolar mixture of chiral (R)- or (S)-Binap and AgClO4. The high stability of the titled catalytic metal-complex to light exposure and its insolubility in toluene made possible its recovery and reutilization in other new process. In order to get a better understanding of the behavior of these chiral catalysts, we have carried out DFT1 calculations demonstrating the experimentally observed high enantio- and endo-selectivity through a very asynchronous transition state.
Najera, Carmen,de Gracia Retamosa,Sansano, Jose M.,Cozar, Abel de,Cossio, Fernando P.
experimental part
p. 2913 - 2923
(2009/07/11)
Catalytic enantioselective 1,3-dipolar cycloaddition reactions of azomethine ylides and alkenes by using phosphoramidite-silver(I) complexes
(Chemical Presented) Silver catalysts: A novel chiral phosphoramidite -silver perchlorate complex has been used for the synthesis of highly substituted pyrolidine rings. This method is valuable for the synthesis of biologically active α-substituted prolines by using hindered dipoles generated from α-substituted α amino acids (see scheme; DABCO=1,4-diazabicyclo[2.2.2]octane).
Najera, Carmen,Retamosa, M. De Gracia,Sansano, Jose M.
experimental part
p. 6055 - 6058
(2009/03/11)
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