A new route to substituted furocoumarins <i>via</i> copper-catalyzed cyclization between 4-hydroxycoumarins and ketoximes
作者:Tuong A. To、Yen H. Vo、Anh T. Nguyen、Anh N. Q. Phan、Thanh Truong、Nam T. S. Phan
DOI:10.1039/c8ob01064a
日期:——
A newroute to substituted furocoumarins via copper-catalyzed cyclization between 4-hydroxycoumarins and ketoximes was developed. CuBr2 exhibited higher activity than other copper salts, affording the desired furocoumarins in high yields. The transformation proceeded readily in the absence of stoichiometric external oxidants. The significance of this synthetic strategy would be (1) the easily available
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
Metal-Free Synthesis of Furocoumarins: An Approach via Iodine-Promoted One-Pot Cyclization between 4-Hydroxycoumarins and Acetophenones
作者:Phuc H. Pham、Que T. D. Nguyen、Nhu K. Q. Tran、Vu H. H. Nguyen、Son. H. Doan、Hiep Q. Ha、Thanh Truong、Nam T. S. Phan
DOI:10.1002/ejoc.201800983
日期:2018.8.31
An iodine‐mediated one‐pot synthesis of furocoumarins has been developed. The furocoumarins were obtained in high yields in the presence of NH4OAc as an additive, whereas neither acidic nor basic additives were effective.
Abstract Facile synthesis of furo[3,2-c]coumarins (2a–g) via cyclocondensation of 4-hydroxycoumarin and α-tosyloxyketones (1a–g) is described. A plausible mechanism involving C-C bond formation followed by 5-exo-tet cyclization is suggested. GRAPHICAL ABSTRACT