Comparing the Stereoselective Biooxidation of Cyclobutanones by Recombinant Strains Expressing Bacterial Baeyer–Villiger Monooxygenases
作者:Florian Rudroff、Joanna Rydz、Freek H. Ogink、Michael Fink、Marko D. Mihovilovic
DOI:10.1002/adsc.200700072
日期:2007.6.4
cyclobutanone structural motif was investigated using a collection of eight monooxygenases of different bacterial origin. This platform of enzymes is able to perform stereoselective biotransformations on an array of structurally diverse substrates. With several ketone precursors, biooxidations yielded enantiocomplementary butyrolactones as key intermediates for the synthesis of natural products and bioactive compounds
Metal-Free sp<sup>3</sup> C-SCF<sub>3</sub> Coupling Reactions between Cycloketone Oxime Esters and <i>S</i>-trifluoromethyl 4-Methylbenzenesulfonothioate
作者:Xia Zhao、Miaomiao Tian、Liangshuo Ji、Junjie Liu、Kui Lu
DOI:10.1021/acs.orglett.9b04343
日期:2020.2.7
A novel sp3 C-SCF3 coupling reactionbetween cycloketone oxime esters and S-trifluoromethyl 4-methylbenzenesulfonothioate was achieved. Ethanol was found to facilitate this transformation by trapping the sulfonyl cation. The metal-free and photocatalyst-free reaction conditions, as well as the broad substrate scope, make this a green protocol for the synthesis of SCF3-substituted nitriles.
Pd(II)/Brønsted Acid Catalyzed Enantioselective Allylic C–H Activation for the Synthesis of Spirocyclic Rings
作者:Zhuo Chai、Trevor J. Rainey
DOI:10.1021/ja2102407
日期:2012.2.29
A Pd(II)/Brønsted acid catalyzed migratory ring expansion for the synthesis of indene derivatives possessing a stereogenic spirocyclic carbon center was developed. This transformation is believed to mechanistically proceed via enantioselective allylic C-H activation with concomitant semipinacol ring expansion to the nascent π-allylpalladium species. Enantioselectivities as high as 98% ee were attainable
开发了 Pd(II)/Brønsted 酸催化的迁移环扩张,用于合成具有立体螺环碳中心的茚衍生物。这种转变被认为是通过对映选择性烯丙基 CH 活化以及伴随的半频哪醇环扩展到新生的 π-烯丙基钯物质而在机械上进行的。可获得高达 98% ee 的对映选择性。
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
Lewis Base/Brønsted Acid Co‐catalyzed Enantioselective Sulfenylation/Semipinacol Rearrangement of Di‐ and Trisubstituted Allylic Alcohols
accomplished with a chiral Lewis base and a chiral Brønsted acid as cocatalysts, generating various β-arylthio ketones bearing an all-carbon quaternary center in moderate to excellent yields and excellent enantioselectivities. These chiral arylthio ketone products are common intermediates with many applications, for example, in the design of new chiral catalysts/ligands and the totalsynthesis of natural products