(2-chloro-2-nitroethenyl)benzenes as synthons: a general method for the preparation of 2,3-dihydro- 2-nitro-3-phenyl-4H-furo [3,2-c] [1]benzopyran-4-ones and 3-phenyl-4H-furo[3,2-c][1]benzopyran-4-ones
Iodine-mediated formal [3 + 2] annulation for synthesis of furocoumarin from oxime esters
作者:Quyen T. Pham、Phong Q. Le、Ha V. Dang、Hiep Q. Ha、Huong T. D. Nguyen、Thanh Truong、Tri Minh Le
DOI:10.1039/d0ra07566c
日期:——
A novel synthesis of furocoumarins was developed by a reaction between oxime esters and 4-hydroxycoumarins. The reaction was proposed to undergo radical mechanism mediated by iodine, a cheap and common laboratory reagent. Mechanistic studies showed the key for the successful transformation was the presence of α-iodoimine intermediate which facilitated the ring-closing step. The developed conditions
Modular access to furo[3,2-c]chromen-4-ones via Yb(OTf)3-catalyzed [3 + 2] annulation of 4-hydroxycoumarins with β-nitroalkenes
作者:Hua Wang、Qin Ma、Yifei Xu、Yanyan Sun、Siyuan Zhao、Shaoyin Wang、Xinwei He
DOI:10.1039/d4ra03962a
日期:——
A facile and efficient strategy for modular access to furo[3,2-c]chromen-4-ones using 4-hydroxycoumarin and β-nitroalkenes via Lewis acid-catalyzed formal [3 + 2] annulation protocol is described. This reaction proceeds via cascade Michaeladdition/nucleophilic addition/elimination in the presence of Yb(OTf)3, which involves the formation of two new σ (C-C and C-O) bonds for the construction of a novel