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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Aminocatalytic asymmetric [4 + 2]-annulation to access functionally rich hexahydrospiroindole pyrazolones
Madavi S Prasad1, Murugesan Sivaprakash1, A Palanichamy1
1Asymmetric synthesis and catalysis laboratory, Department of Chemistry, Central University of Tamil Nadu (CUTN), Tiruvarur-610 005, India. shivaprasad@cutn.ac.in.
Abstract:
Herein, we report the [4 + 2]-annulation of in situ generated trienamine from 2-(E)-benzylidine-3-pyrrolidinyl acraldehyde with pyrazolone olefins for the first time. It is a robust protocol for the synthesis of biologically appealing functionally rich hexahydrospiroindole pyrazolones which is reflected in excellent yields, stereoselectivity, operational simplicity and broad substrate scope as demonstrated in this paper. Furthermore, we have also explored the synthetic applications of optically pure hexahydrospiroindole pyrazolone to construct biologically important alkylated hexahydrospiroindole pyrazolone and octahydrospiroindole pyrazolone with good yields and high selectivity.
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