Scope and Limitations of the Photooxidations of 2-(α-Hydroxyalkyl)furans: Synthesis of 2-Hydroxy-exo-brevicomin
摘要:
Photooxygenation of 2-(alpha-hydroxyalkyl)furans at 5 degrees C in MeOH followed by in situ reduction affords, in one synthetic operation, 6-hydroxy-3(2H)-pyranones and/or 5-hydroxy-2(5H)-furanones. The relative ratio of the final products is highly dependent on the substitution of the starting furan substrate. Photooxygenation of 2-(alpha,beta-dihydroxyalkyl)furans followed by in situ reduction and ketalization with acid rapidly provides the 6,8-dioxabicyclo[3.2.1]oct-3-en-2-one framework. This new methodology was successfully applied to the synthesis of 2-hydroxy-exo-brevicomin.
C–H Alkenylation of Heteroarenes: Mechanism, Rate, and Selectivity Changes Enabled by Thioether Ligands
作者:Bradley J. Gorsline、Long Wang、Peng Ren、Brad P. Carrow
DOI:10.1021/jacs.7b03887
日期:2017.7.19
catalytic intermediate in these reactions may also account for unusual catalyst-controlled site selectivity wherein C–H alkenylation of five-atom heteroarenes can occur under electronic control with thioether ligands even when this necessarily involves reaction at a more hindered C–H bond. The thioether effect also enables short reaction times under mild conditions for many O-, S-, and N-heteroarenes (55 examples)
Direct lithiation of functionally substituted acrylic acid derivatives
作者:R.R. Schmidt、R. Hirsenkorn
DOI:10.1016/s0040-4020(01)91922-2
日期:1983.1
butenolides, tetronates, cyclopentenones and derivatives, which are portions of many natural products. A wide variety of α- and β-substituents are compatible with this lithiation: alkyl-, aryl- and electron donating substituents in α-position or for instance an electron withdrawing ester group in β-position. Lithiation of aminomethylene malonitrile derivative 17 led to a new azafulvene 18.
The Reaction of 2-Methylfuran with Methyl Acrylate. Unusual Formation of 1,1′-Bis(5-methyl-2-furyl)ethane and Methyl 3,3′-Bis(5-methyl-2-furyl)propionate
作者:Osamu Maruyama、Yuzo Fujiwara、Hiroshi Taniguchi
DOI:10.1246/bcsj.54.2851
日期:1981.9
The reaction of 2-methylfuran with methyl acrylate in the presence of Pd(OAc)2 gave unusual products such as 1,1′-bis(5-methyl-2-furyl)ethane (22%) and methyl 3,3′-bis(5-methyl-2-furyl)propionate (10%) along with the usual aromatic substitution product. This is a marked contrast to the reaction of furan with olefins.