The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
作者:Huan Guo、Jing Li、Delong Liu、Wanbin Zhang
DOI:10.1002/adsc.201700846
日期:2017.10.25
A ruthenocenyl phosphino‐oxazoline‐ruthenium complex (RuPHOX−Ru) catalyzedasymmetrichydrogenation of α‐aryl keto acids has been successfully developed, affording the corresponding chiral α‐aryl α‐hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed
已成功开发了钌烯基膦基-恶唑啉-钌络合物(RuPHOX-Ru)催化的α-芳基酮酸不对称氢化反应,可提供高收率和ee高达97%的相应手性α-芳基α-羟基羧酸。该反应可以在相对较低的催化剂负载量(至多5000 S / C)下以克为单位进行,所得产物可以转化为几种手性结构单元,生物活性化合物和手性药物。
The Application of 1,2-Oxazinanes as Chiral Cyclic Weinreb Amide-Type Auxiliaries Leading to a Three-Component, One-Pot Reaction
作者:Gerhard Hilt、Jan Fährmann、Ludmila Hermann
DOI:10.1055/a-1683-0484
日期:2022.4
1,2-Oxazines were synthesised via a copper-catalysed aerobic acylnitrosoDiels–Alderreaction from 1,4-disubstituted 1,3-dienes and N-Boc-hydroxylamine. From this, 1,2-oxazinanes were obtained in a novel follow-up reaction path. The stability of several 1,2-oxazines and 1,2-oxazinanes towards organometallic compounds was tested to rate their operability as cyclic chiral Weinreb amide auxiliaries.
DC-SIGN and Langerin are two C-type lectins involved in the initial steps of HIV infections: the former acts as a viral attachment factor and facilitates viral invasion of the immune system, the latter has a protective effect. Potential antiviral compounds targeted against DC-SIGN were synthesized using a common fucosylamide anchor. Their DC-SIGN affinity was tested by SPR and found to be similar to that of the natural ligand Lewis-X (LeX). The compounds were also found to be selective for DC-SIGN and to interact only weakly with Langerin. These molecules are potentially useful therapeutic tools against sexually transmitted HIV infection.
Cheap, readily available, air stable, nontoxic, and environmentally benign iron salts such as Fe(acac)3 are excellent precatalysts for the cross-coupling of Grignardreagents with alkenyl triflates and acid chlorides. Moreover, it is shown that dichloroarene and -heteroarene derivatives as the substrates can be selectively monoalkylated by this method. All cross-coupling reactions proceed very rapidly
廉价,容易获得,空气稳定,无毒且对环境无害的铁盐,例如Fe(acac)3是格氏试剂与链烯基三氟甲磺酸酯和酰氯交叉偶联的出色的预催化剂。此外,显示出通过该方法可以将作为底物的二氯亚芳基和-杂亚芳基衍生物选择性地单烷基化。所有交叉偶联反应在特别温和的条件下均能非常快速地进行,结果证明与两个反应伙伴中的各种官能团均相容。对制备结果的详细分析表明,铁催化的碳键形成可以通过不同的途径发生。因此,甲基卤化镁的反应可能包含铁酸盐配合物作为活性成分,而格氏试剂与两个或多个碳原子的反应则受到形式组成[Fe(MgX)2 ]的高度还原的铁簇的影响。n原位生成。使用复杂的[Me 4 Fe] Li 2的对照实验证实了这一解释。
Synthesis of the C(1)–C(16) fragment of bryostatins using an ‘ene’ reaction between an allylsilane and an alkynone
作者:Matthew O’Brien、Eric J. Thomas
DOI:10.1016/j.tet.2011.09.064
日期:2011.12
mediated ‘ene’ reaction between (4R)-4,5-bis-(tert-butyldimethylsilyloxy)-2-(trimethylsilylmethyl)pent-1-ene (43) and (5S,7R,9S)-5,11-dibenzyloxy-4,4-dimethyl-7,9-dihydroxy-7,9-O-isopropylideneundec-1-yn-3-one (53) gave the (E)-vinylsilane 54 with excellent stereoselectivity. Simultaneous deprotection and cyclisation via a stereoselective oxy-Michael reaction gave the bicyclicacetal 57 after treatment