双官能N,N- '二氧化物催化剂已经被开发用于α的高度对映选择性的硅氰化反应,α二烷氧基酮。此过程中,通过催化的原位制备的脯氨酸衍生Ñ,Ñ '二氧化物2b中,所产生的相应的氰醇三甲基甲硅烷基醚以优良产率(高达99%)的高对映选择性(高达93%ee)的。根据线性效应,1 H NMR谱图,分离的氰醇以及催化剂的NH和N-氧化物部分的作用,提出了合理的机理。
Highly efficient and recyclable chiral Pt nanoparticle catalyst for enantioselective hydrogenation of activated ketones
作者:Xiuru Xue、Pu Chen、Peng Xu、Yanhua Wang
DOI:10.1016/j.catcom.2018.03.012
日期:2018.5
phase-separable chiral Pt nanoparticle catalyst exhibited excellent ee (>99%) in the enantioselectivehydrogenation of activated ketones for preparing chiral α-hydroxy acetals and chiral 1,2-diols. More importantly, the chiral catalyst could be easily separated by phase separation and directly reused in the next cycle without any loss in catalytic activity and enantioselectivity, even in the gram-scale reaction
Zeolite-catalysed conversion of C3 sugars to alkyl lactates
作者:Paolo P. Pescarmona、Kris P. F. Janssen、Chloë Delaet、Christophe Stroobants、Kristof Houthoofd、An Philippaerts、Chantal De Jonghe、Johan S. Paul、Pierre A. Jacobs、Bert F. Sels
DOI:10.1039/b921284a
日期:——
The direct conversion of C3 sugars (or trioses) to alkyl lactates was achieved using zeolite catalysts. This reaction represents a key step towards the efficient conversion of bio-glycerol or formaldehyde to added-value chemicals such as lactate derivatives. The highest yields and selectivities towards the desired lactate product were obtained with Ultrastable zeolite Y materials having a low Si/Al ratio and a high content of extra-framework aluminium. Correlating the types and amounts of acid sites present in the different zeolites reveals that two acid functions are required to achieve excellent catalysis. Brønsted acid sites catalyse the conversion of trioses to the reaction intermediate pyruvic aldehyde, while Lewis acid sites further assist in the intramolecular rearrangement of the aldehyde into the desired lactate ester product. The presence of strong zeolitic Brønsted acid sites should be avoided as much as possible, since they convert the intermediate pyruvic aldehyde into alkyl acetals instead of lactate esters. A tentative mechanism for the acid catalysis is proposed based on reference reactions and isotopically labelled experiments. Reusability of the USY catalyst is demonstrated for the title reaction.
利用沸石催化剂实现了 C3 糖(或三糖)到烷基乳酸盐的直接转化。该反应是将生物甘油或甲醛高效转化为高附加值化学品(如乳酸衍生物)的关键一步。使用具有低硅/铝比率和高框架外铝含量的超稳定沸石 Y 材料可获得最高的产率和对所需乳酸盐产品的选择性。对不同沸石中存在的酸性位点的类型和数量进行对比后发现,要实现出色的催化效果,需要两种酸性功能。布氏酸位点催化三聚物转化为反应中间产物丙酮酸醛,而路易斯酸位点则进一步帮助醛分子内重排为所需的乳酸酯产物。应尽量避免出现强沸石布氏酸位点,因为它们会将中间产物丙酮酸醛转化为烷基乙醛,而不是乳酸酯。根据参考反应和同位素标记实验,提出了酸催化的初步机制。证明了 USY 催化剂在标题反应中的重复使用性。
Ethers of esters of lactic acid
申请人:CARBIDE &
公开号:US02421378A1
公开(公告)日:1947-06-03
Gordeeva, G. N.; Kalashnikov, S. M.; Imashev, U. B., Journal of Organic Chemistry USSR (English Translation), 1983, vol. 19, p. 1739 - 1740
作者:Gordeeva, G. N.、Kalashnikov, S. M.、Imashev, U. B.
DOI:——
日期:——
GORDEEVA, G. N.;KALASHNIKOV, S. M;IMASHEV, U. B., ZH. ORGAN. XIMII, 1983, 19, N 9, 1979-1980
作者:GORDEEVA, G. N.、KALASHNIKOV, S. M、IMASHEV, U. B.