Regioselective synthesis of 3,5-diaryl-4-methylisoxazoles
摘要:
A new class of isoxazole derivatives, namely 2-(3-aryl-4-methylisoxazol-5-yl)phenols, has been efficiently synthesized through the regioselective reaction of 2-aryl-3-methylchromones with hydroxylamine. The products were characterized by spectroscopic methods and X-ray crystallography..
Dynamic Kinetic Resolution of Secondary Diols via Coupled Ruthenium and Enzyme Catalysis
作者:B. Anders Persson、Fernando F. Huerta、Jan-E. Bäckvall
DOI:10.1021/jo990447u
日期:1999.7.1
Enzymatic acylation of secondary symmetrical diols (as meso/dlmixtures) in combination with ruthenium-catalyzed isomerization of the diol led to efficient dynamic kineticresolution. In this way, a meso/dlmixture of the diol was transformed to enantiomerically pure (R,R)-diacetate, making efficient use of all the diol material. For some of the flexible substrates, substantial amounts of meso-diacetates
New air-stable iron catalyst for efficient dynamic kinetic resolution of secondary benzylic and aliphatic alcohols
作者:Qiong Yang、Na Zhang、Mingke Liu、Shaolin Zhou
DOI:10.1016/j.tetlet.2017.05.038
日期:2017.6
catalyst system for the dynamic kineticresolution of secondaryalcohols by combining the enzymatic resolution with an iron-catalyzed racemization. A new air-stable tricarbonyl (cyclopentadienone)iron complex is identified as the active racemization catalyst for this transformation without any additive. Various substrates including benzylic, heteroaromatic, aliphatic alcohols can be used and afford the
How Much Does the Hybridization of a Carbon Atom Affect the Transmission of the Substituent Effect on the Chemical Shift?
作者:Eun Jeong Jeong、In-Sook Han Lee
DOI:10.1002/bkcs.10067
日期:2015.1
systematically examined to find out the substituent effect on the chemical shift. The values of the chemical shift of the carbonyl carbon showed an inverse correlation with the Hammett σ values, and the magnitude of the slope was the largest with the propiolates. The α carbons of acrylates and propiolates also showed an inverse correlation with much smaller values of the slopes than those of the carbonyl carbons;
1 H和13系统检查了丙酸,丙烯酸和丙酸的芳基酯的13 C NMR光谱,以了解取代基对化学位移的影响。羰基碳的化学位移值与Hammettσ值呈反比关系,且斜率的大小与丙酸酯的比值最大。丙烯酸酯和丙酸酯的α碳也显示出负相关,其斜率值比羰基碳小得多。但是那些丙酸的人绝对没有关联。但是,丙烯酸酯和丙酸酯的β碳与较大的斜率值呈正相关。斜率的符号和大小可以通过取代基电子效应通过键和空间的传递来理解。苯环的13 C化学位移值。
Synthesis, experimental and theoretical study of novel 2-haloalkyl (-CF2H, -CCl2H, -CF2CF3)-, 3-bromo and bromomethyl substituted chromones
作者:Ena G. Narváez O、Pablo M. Bonilla V.、Daniel A. Zurita、Christian D. Alcívar L.、Jorge Heredia-Moya、Sonia E. Ulic、Jorge L. Jios、Oscar E. Piro、Gustavo A. Echeverría、Peter Langer
DOI:10.1016/j.jfluchem.2020.109717
日期:2021.2
2-haloalkyl (-CF2H, -CCl2H, -CF2CF3) and 3-bromo and bromomethyl substituents were synthesized. The novel compounds were studied by DFT calculations and characterized by vibrationalspectroscopy (IR and Raman) in solid state, and NMR (1H, 13C and 19F) and UV–vis spectroscopy in solution. The crystal structure of 3-dibromomethyl-2-difluoromethyl chromone was determined by X-ray diffraction. Due to extended
Flavanonol derivatives and hair-nourishing, hair growing compositions
申请人:Kao Corporation
公开号:US05702691A1
公开(公告)日:1997-12-30
The present invention relates to flavanonol derivatives represented by formula (1): ##STR1## (wherein R.sup.1 represents an alkyl group, and each of R.sup.2 and R.sup.3 represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxyl group which may have a substituent, a hydroxyl group, a cyano group, or a halogen atom), as well as to hair-nourishing and hair-growing compositions containing the derivatives. The compounds accelerate differentiation and proliferation of hair matrix cells, thereby exhibiting remarkable hair-nourishing and hair-growing effects.