Exceptional activity of gallium(<scp>iii</scp>) chloride and chlorogallate(<scp>iii</scp>) ionic liquids for Baeyer–Villiger oxidation
作者:Magdalena Markiton、Anna Chrobok、Karolina Matuszek、Kenneth R. Seddon、Małgorzata Swadźba-Kwaśny
DOI:10.1039/c6ra03435g
日期:——
a range of metal chlorides in different solvents, and in neat chlorogallate(III) ionic liquids. The extremely high activity of GaCl3 in promoting oxidation with H2O2, irrespective of solvent, was reported for the first time. The activity of all other metal chlorides was strongly solvent-dependent. In particular, AlCl3 was very active in a protic solvent (ethanol), and tin chlorides, SnCl4 and SnCl2
使用H 2 O 2作为氧化剂,使用一系列金属氯化物在不同溶剂中和纯净的氯镓酸盐(III)离子液体中,系统研究了Bayerer-Villiger对环酮的氧化。首次报道了GaCl 3在促进H 2 O 2氧化方面的极高活性,而与溶剂无关。所有其他金属氯化物的活性都高度依赖溶剂。特别是,AlCl 3在质子溶剂(乙醇)中非常活泼,氯化锡,SnCl 4和SnCl 2,在非质子传递溶剂(甲苯和二恶烷)中具有活性。为了消除对挥发性有机溶剂的需求,使用路易斯酸性氯镓酸盐(III)离子液体代替GaCl 3,在环境条件下,其在1-120分钟内通常可产生89-94%的内酯收率。Raman和71 Ga NMR光谱研究表明,在GaCl 3和galgallate(III)离子液体系统中的活性物质均为chlorohydroxygallate(III)阴离子[GaCl 3 OH] -,它们是GaCl 3部分水解的产物。和氯
Photoinduced Fragmentation Borylation of Cyclic Alcohols and Hemiacetals
作者:Chao Shu、Rudrakshula Madhavachary、Adam Noble、Varinder K. Aggarwal
DOI:10.1021/acs.orglett.0c02513
日期:2020.9.18
conveniently prepared by radical-mediated ring opening of cyclic alcohols and hemiacetals, respectively. The reactions proceed under mild conditions in the absence of additives or photocatalysts, display excellent functional group tolerance, and are shown to allow cleavage of 4-, 5-, 6-, and 7-membered ring substrates. The mechanism proceeds via sequential homolytic N–O and C–C bond cleavages, the latter