Mono[6-(2-mercaptoethylamino)-6-deoxy]-β-cyclodextrin as an efficient glyoxalase mimic
摘要:
Trifunctionalmono[6-(2-mercaptoethylamino)-6-deoxy]-beta-cyclodextrin (MACD) has been prepared and used as a glyoxalase model. When 2-naphthylglyoxal (NAGO) is employed as a diagnostic substrate, MACD shows an overall activity greater than the reference compound 2-(dimethylamino)ethanethiol (DAET) at around pH 9; MACD favours remarkably the preequilibrium alpha-keto hemithioacetal formation, but slightly decelerates the follow-up rearrangement. The pH and kinetic isotope effects on the rate have revealed the mechanistic difference between the MACD- and DAET-promoted reactions.
Coordination-Induced Stereocontrol over Carbocations: Asymmetric Reductive Deoxygenation of Racemic Tertiary Alcohols
作者:Mayuko Isomura、David A. Petrone、Erick M. Carreira
DOI:10.1021/jacs.9b00862
日期:2019.3.20
intermediate tertiary carbocations. This approach has been implemented to achieve the first example of enantioselective reductive deoxygenation of tertiaryalcohols. This reduction occurs with high enantio- (up to 96% ee) and regioselectivity (up to >50:1 rr) by applying a novel Hantzsch ester analogue as a convenient hydride source. In-depth mechanistic studies support the involvement of a tertiary carbocation
A simple, cost-effective method for deuteration of carbonyl compounds employing pyrrolidine as catalyst and D2O as deuterium source was described. High degree of deuterium incorporation (up to 99%) and extensive functional group tolerance were achieved. It is the first time that secondary amines are used as catalysts for H/D exchange of carbonyl compounds, which also allow the deuteration of complex pharmaceutically interesting substrates. A possible catalytic mechanism, based on the hydrolysis of 1-pyrrolidino-1-cyclohexene, for this pyrrolidine-catalyzed H/D exchange reaction has been proposed.
Conversion of Carbonyl Compounds to Olefins
<i>via</i>
Enolate Intermediate
作者:Zhi‐Chao Cao、Pei‐Lin Xu、Qin‐Yu Luo、Xiao‐Lei Li、Da‐Gang Yu、Huayi Fang、Zhang‐Jie Shi
DOI:10.1002/cjoc.201800554
日期:2019.8
A general and efficient protocol to synthesize substituted olefins from carbonyl compounds via nickel catalyzed C—O activation of enolates was developed. Besides ketones, aldehydes were also suitable substrates for the presented catalytic system to produce di‐ or tri‐ substituted olefins. It is worth noting that this approach exhibited good tolerance to highly reactive tertiary alcohols, which could
work reports a metal-free method for deuteriumlabeling covering a broad range of substrate including phenolic compounds (i.e. flavonoids and stilbenes), indoles, pyrroles, carbonyl compounds, and steroids. This method was also applied for commonly used drugs such as loxoprofen, haloperidol, stanolone, progesterone, androstenedione, donepezil, ketorolac, adrenosterone, cortisone, pregnenolone, and dexamethasone
在这里,我们揭示了一种简单的卤化氘 (DX) 生成方法,该方法由合成化学实验室中现成的普通且廉价的试剂制成,i . e . 在温和条件下,异戊二烯基、烯丙基和炔丙基卤化物。我们设想,原位生成酸卤化氘可用于酸催化反应,并可用于有机催化氘化。本工作报告了一种无金属氘标记方法,覆盖范围广泛的底物,包括酚类化合物(即. 类黄酮和芪)、吲哚、吡咯、羰基化合物和类固醇。该方法也适用于常用药物,如洛索洛芬、氟哌啶醇、甾烷酮、黄体酮、雄烯二酮、多奈哌齐、酮咯酸、肾上腺素、可的松、孕烯醇酮和地塞米松。这项工作证明了一些氘代化合物的克级无色谱合成。这项工作提供了一种简单、清洁且无副产物的位点选择性氘代,并且氘代产物无需色谱分离即可获得。当将这些引发剂用于其他酸催化反应时,DX 的氘同位素效应可能会提供不同于使用普通酸的反应所获得的产物。虽然异戊二烯卤化物自发转化为酸的机制尚不清楚,
作者:Marcileia Zanatta、Francisco P. dos Santos、Cristina Biehl、Graciane Marin、Gunter Ebeling、Paulo A. Netz、Jairton Dupont
DOI:10.1021/acs.joc.6b03029
日期:2017.3.3
for the H/Dexchange reaction of various substrates using CDCl3 as D source, without the addition of any extra bases or metal. High deuterium incorporation (up to 49%) in acidic C–H bonds of ketone and alkyne substrates (pKa from 18.7 to 28.8) was found at room temperature. The reaction proceeds through the fast and reversible deuteration of the 2-methyl H of the imidazolium cation followed by D transfer
与碱性阴离子(例如碳酸氢盐,脯氨酸盐和咪唑酸盐)缔合的简单1,2,3-三烷基咪唑鎓阳离子是使用CDCl 3作为D源进行各种底物H / D交换反应的活性催化剂,而无需添加任何多余的碱或金属。酮和炔烃底物的酸性C–H键中氘的高掺入量(最高49%)(p K a在室温下发现(从18.7到28.8)。反应通过咪唑鎓阳离子的2-甲基H的快速可逆氘化进行,然后D转移至底物。IL充当中性碱催化剂,其中在反应过程中保持接触离子对。碱性活性位点归因于阴离子中存在一个偏远的碱性位点,即碳酸氢根的OH,脯氨酸根的NH和咪唑基阴离子中的活化水。详细的动力学实验表明,由于涉及溶剂对离子液体进行氘化的快速可逆反应,因此该反应在底物上相对于离子液体为一级伪零级。