Regioselective Synthesis of Multisubstituted Furans via Metalloradical Cyclization of Alkynes with α-Diazocarbonyls: Construction of Functionalized α-Oligofurans
作者:Xin Cui、Xue Xu、Lukasz Wojtas、Martin M. Kim、X. Peter Zhang
DOI:10.1021/ja309446n
日期:2012.12.12
five-membered furan structures. The Co(II) complex of 3,5-Di(t)Bu-IbuPhyrin, [Co(P1)], is effective in catalyzing the metalloradical cyclization reaction under neutral and mild conditions. The [Co(P1)]-catalyzed process tolerates a wide range of α-diazocarbonyls and terminal alkynes with varied steric and electronic properties, producing polyfunctionalized furans with complete regioselectivity. The catalytic
The [Cu(acac)2]‐catalyzed reactions of several tertiary enaminones with three diazocarbonylcompounds, i.e., dimethyl diazomalonate, ethyl diazoacetoacetate, and ethyl diazoacetate, yielded amino‐ and additionally carbonyl‐substituted dihydrofurans, together with further furan derivatives. Due to the conjugation of α‐carbonyl/α‐Ph groups, reactions proceeded only via 1,5‐electrocyclization of corresponding
Facile One-Pot Synthesis of Di- and Tri-Substituted Furans From Acyl Isocyanates Using Trimethylsilyldiazomethane
作者:Toyohiko Aoyama、Yoshiyuki Hari、Tomoe Iguchi
DOI:10.1055/s-2004-822397
日期:——
The Diels-Alder reaction of 2-substituted 4-(trimethyl-silyloxy)oxazoles, which were prepared in situ from trimethylsilyldiazomethane and acylisocyanates, with dimethyl acetylenedicarboxylate or ethyl propiolate gave furan-3,4-dicarboxylic or furan-3-carboxylic esters in good yields.
Gold-catalyzed efficient synthesis of 2,4-disubstituted furans from aryloxy-enynes
作者:Ende Li、Wenjun Yao、Xin Xie、Chengyu Wang、Yushang Shao、Yanzhong Li
DOI:10.1039/c2ob07173h
日期:——
(E)-1-aryloxy-1-en-3-ynes has been prepared by Sonogashiracoupling of 2-bromo-3-aryloxypropenoates with terminal alkynes using Pd(PPh3)4 and CuI as the catalysts in Et3N. The resulting enynyl-aryl ethers are found to be highly applicable to the synthesis of 2,4-disubstituted furans with an ester group at C-4 position through an Au/Ag-catalyzed annulation reaction under extremely mild reaction conditions.
Copper-catalyzed synthesis of 1,2,4-trisubstituted pyrroles via cascade reactions of aryloxy-enynes with amines
作者:Ende Li、Xingcan Cheng、Chengyu Wang、Xia Sun、Yanzhong Li
DOI:10.1039/c3ra44595j
日期:——
A highly efficient copper-catalyzed cascade reaction of aryloxy-enynes with amines under mild reaction conditions has been developed. This methodology offers rapid access to 1,2,4-trisubstituted pyrroles in good to excellent yields in a regioselective manner.