摘 要: | The development of novel synthons and efficient methods to synthesize chiral polycyclic indoles has been a hot topic in organic synthesis and medicinal chemistry owing to their broad applications in medicines,pesticides,and other functional molecules.Here,we disclosed novel indolyl substituted metal-allyl zwitterionic intermediates through the decarboxylation of conveniently available vinyl indoloxazolidones,which could be regarded as two types of dipolar species through the anionic delocalization.The palladium-π-allyl species tended to serve as an all-carbon 1,3-dipole in the asymmetric3+2]cycloaddition with electrondeficient alkenes,which furnished polysubstituted cyclopentab]indoles with high regio-and stereoselectivities.Meanwhile,the iridium-π-allyl species was recognized as an aza-1,3-dipole in asymmetric3+2]cycloaddition with in situ generated C1 ammonium enolates,affording pyrrolo1,2-α]indoles with high diastereo-and enantioselectivities.In addition,the dipolar cycloadditions could be easily scaled-up and several synthetic transformations of the cycloadducts were demonstrated for the rapid synthesis of diverse chiral polycyclic indoles.
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