Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromi...Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.展开更多
Spiro compounds are widely prevalent in biological activities and natural products.However,developing new strategies for their efficient synthesis and derivatization remains a challenge.Outstanding progress has been m...Spiro compounds are widely prevalent in biological activities and natural products.However,developing new strategies for their efficient synthesis and derivatization remains a challenge.Outstanding progress has been made in the synthesis of spiro compounds through dearomatization of aromatic compounds,most of them are mediated by the hypervalent iodine reagents.Herein,we report a method of anodic oxidation spiroamination and spirolactonization of anisole derivatives with concomitant cathodic reduction of protons in the absence of hypervalent iodine reagents.A wide variety of spiropyrrolidines and spirolactones with diverse functional groups made useful scaffolds in this transformation,with yields up to 97%.Moreover,hectogram-scale synthesis could supply target product with 83% yield in a flow electrochemical cell using carbon paper as the anode and nickel plate as the cathode,demonstrating the potential application of this method.展开更多
文摘Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.
基金supported by the National Natural Science Foundation of China(no.22031008)the Science Foundation of Wuhan(no.2020010601012192).
文摘Spiro compounds are widely prevalent in biological activities and natural products.However,developing new strategies for their efficient synthesis and derivatization remains a challenge.Outstanding progress has been made in the synthesis of spiro compounds through dearomatization of aromatic compounds,most of them are mediated by the hypervalent iodine reagents.Herein,we report a method of anodic oxidation spiroamination and spirolactonization of anisole derivatives with concomitant cathodic reduction of protons in the absence of hypervalent iodine reagents.A wide variety of spiropyrrolidines and spirolactones with diverse functional groups made useful scaffolds in this transformation,with yields up to 97%.Moreover,hectogram-scale synthesis could supply target product with 83% yield in a flow electrochemical cell using carbon paper as the anode and nickel plate as the cathode,demonstrating the potential application of this method.
