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 5-hydroperoxyfuran-2(5H)-ones 3 are synthesized by acid hydrolysis of the dihydrofurans 1 which are prepared in one-pot procedure by reaction of the corresponding furans 4 with singlet oxygen and methanol. The synthetic method has a wide range of applicability; however, compounds 3 unsubstituted at C-4 cannot be prepared since the corresponding dihydrofurans 1 are not formed.
Functionalized methyl cis-4-oxoalk-2-enoates 2 are synthesized in a one-pot procedure by singlet oxygen oxygenation of the corresponding 2-methoxyfurans 1 in methanol and reduction of the resulting hydroperoxides 4 and 5 by the sulfides 6 which are selectively oxidized into the sulfoxides 7. The synthetic method has a wide range of applicability and affords compounds 2 stereoselectively and in good yields; concomitantly the sulfoxides 7 are obtained in excellent yields.
Tuning of Regioselectivity in Inorganic Iodide-Catalyzed Alkylation of 2-Methoxyfurans via Electronic and Steric Effects
作者:Jie Chen、Shengjun Ni、Shengming Ma
DOI:10.1002/adsc.201100337
日期:2012.4.16
may be cleaved to afford the corresponding lactonic anion. Due to the presence of an electron‐withdrawing group at the 3‐position, the alkylation with normal organic iodides occurred at the 3‐position highly regioselectively. However, when electron‐deficient allylic iodides with an electron‐withdrawing group at the 2‐position were used the 5‐alkylation products were formed as the major products with sodium
The first nucleophilic aromatic substitution of suitably activated 2-methoxyfurans with Grignard reagents
作者:M.Rosaria Iesce、M.Liliana Graziano、Flavio Cermola、Stefania Montella、Lucrezia Di Gioia
DOI:10.1016/s0040-4039(03)01430-8
日期:2003.7
The reaction of 2-methoxyfuroates 1 with Grignardreagents 2 leads to tertiary alcohols or SNAr products depending on the position of the alkoxycarbonyl group. OMe-Displacement occurs only for 3-substituted derivatives. It takes place even for 3-acetyl-2-methoxyfuran while the presence of a further ester function at 4 position induces the formation of the sole 4-tertiary alcohol. The OMe-substitution