Binap-gold(I) versus Binap-silver trifluoroacetate complexes as catalysts in 1,3-dipolar cycloadditions of azomethine ylides |
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Authors: | Martín-Rodríguez María Nájera Carmen Sansano José M de Cózar Abel Cossío Fernando P |
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Institution: | Química Orgánica e Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo 99, 03080 Alicante, Spain. |
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Abstract: | The 1,3-dipolar cycloaddition between azomethine ylides and alkenes is efficiently catalysed by {(S(a))-Binap-Au(tfa)}(2)] (Binap=2,2'-bis(diphenylphosphino)-1,1'-binaphthyl; tfa=trifluoroacetyl). Maleimides, 1,2-bis(phenylsulfonyl)ethylene, chalcone and nitrostyrene were suitable dipolarophiles even when using sterically hindered 1,3-dipole precursors. The results obtained in these transformations improve the analogous ones obtained in the same reactions catalysed by Binap-Ag(tfa)]. In addition, computational studies have also been carried out to demonstrate both the high enantioselectivity exhibited by the chiral gold(I) complex, and the non-linear effect observed in this transformation. |
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Keywords: | asymmetric synthesis azomethine cycloaddition gold silver |
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