A catalytic hypervalent iodine oxidation of p-dialkoxybenzenes using 4-iodophenoxyacetic acid (1) and 2KHSO5 x KHSO4 x K2SO4 (Oxone) was developed. Reaction of p-dialkoxybenzenes (2) with a catalytic amount of 1 in the presence of Oxone as a co-oxidant in 2,2,2-trifluoroethanol-water (1 : 2) gave the corresponding p-quinones (3) in excellent yields without purification. This procedure was applied to
开发了使用4-碘苯氧基乙酸(1)和2KHSO5 x KHSO4 x K2SO4(Oxone)对对二烷氧基苯进行催化的高价碘氧化。在作为辅助氧化剂的Oxone存在下,对二烷氧基苯(2)与催化量为1的反应在2,2,2-三氟乙醇-水(1:2)中反应,生成了相应的对苯醌(3)无需纯化即可产生。该程序用于合成德国小Bl Blattella germanica的性信息素blattellaquinone(9)。
2,5-Dihydroxybenzyl and (1,4-Dihydroxy-2-naphthyl)methyl, Novel Reductively Armed Photocages for the Hydroxyl Moiety
作者:Alexey P. Kostikov、Vladimir V. Popik
DOI:10.1021/jo701426j
日期:2007.11.1
[Graphics]Irradiation of alcohols, phenols, and carboxylic acids "caged" with the 2,5-dihydroxybenzyl group or its naphthalene analogue results in the efficient release of the substrate. The initial byproduct of the photoreaction, 4-hydroxyquinone-2-methide, undergoes rapid tautomerization into methyl p-quinone. The UV spectrum of the latter is different from that of the caging chromophore, thus permitting selective irradiation of the starting material in the presence of photochemical products. These photoremovable protecting groups can be armed in situ by the reduction of photochemically inert p-quinone precursors.
Xu Yao-Chang, Lebeau Elaine, Walker Clint, Tetrahedron Lett, 35 (1994) N 34, S 6207-6210