Probing α‐Amino Aldehydes as Weakly Acidic Pronucleophiles: Direct Access to Quaternary α‐Amino Aldehydes by an Enantioselective Michael Addition Catalyzed by Brønsted Bases
The high tendency of α‐amino aldehydes to undergo 1,2‐additions and their relatively low stability under basic conditions have largely prevented their use as pronucleophiles in the realm of asymmetric catalysis, particularly for the production of quaternary α‐amino aldehydes. Herein, it is demonstrated that the chemistry of α‐amino aldehydes may be expanded beyond these limits by documenting the first
A chiral C2-symmetric 1,2-diamine based on a 1,1′-bi(tetrahydroisoquinoline) scaffold was found to be an efficientligand for the enantioselective NiII-catalysed Michaeladdition of malonic esters to conjugated nitroalkenes. The reactions proceed with 92–99 % yield and 91–99 % enantioselectivity even at elevated temperatures. The solid-state structure of the catalyst precursor revealed intramolecular
A new and efficient one-pot strategy combining catalyst-free synthesis and iodinecatalysis has been developed for the synthesis of dihydrofuropyrimidines and spirodihydrofuropyrimidine pyrazolones. This approach affords products in moderate to high yields (up to 96%) with excellent diastereoselectivities (up to >25 : 1 dr). The reaction is simple to carry out and is metal-free.
DMAP Catalyzed Domino Rauhut–Currier Cyclization Reaction between Alkylidene Pyrazolones and Nitro-olefins: Access to Tetrahydropyrano[2,3-<i>c</i>]pyrazoles
作者:Nimisha Bania、Buddhadeb Mondal、Sounak Ghosh、Subhas Chandra Pan
DOI:10.1021/acs.joc.0c02871
日期:2021.3.5
Herein, we employ unsaturated pyrazolones in the Rauhut–Currier reaction for the first time. A domino Rauhut–Currier cyclization reaction has been developed between unsaturated pyrazolones and nitro-olefins. The trisubstituted tetrahydropyrano[2,3-c]pyrazoles were obtained in moderate to high yields with excellent diastereoselectivities. A few applications including a synthesis of disubstituted tetrahydropyrano[2
在本文中,我们首次在Rauhut-Currier反应中使用了不饱和吡唑啉酮。在不饱和吡唑啉酮和硝基烯烃之间发展了多米诺Rauhut-Currier环化反应。三取代四氢吡喃并[2,3- c ]吡唑以中等至高收率获得,具有非对映选择性。已经证明了包括合成二取代的四氢吡喃并[2,3- c ]吡唑在内的一些应用。还使用手性DMAP催化剂研究了该方法的初步催化不对称形式。
Asymmetric construction of six vicinal stereogenic centers on hexahydroxanthones <i>via</i> organocatalytic one-pot reactions
作者:Min Zhang、Xue-Wen He、Ya Xiong、Xiong Zuo、Wei Zhou、Xiong-Li Liu
DOI:10.1039/d1cc02570h
日期:——
herein we report an organocatalytic Michael–Michael–Aldol-decarboxylation reaction that provides efficient access to biologically interesting fully substituted hexahydroxanthones bearing six contiguous stereogenic centers from readily accessible materials in acceptable yields (up to 63%) and excellent stereoselectivities (up to 10 : 1 dr and >99% ee). In other words, the reaction efficiently produces
受六氢氧杂蒽酮的化学和生物学的启发,我们在此报告了一种有机催化迈克尔-迈克尔-羟醛脱羧反应,该反应可以有效地从易于获得的材料中以可接受的产率(高达 63%)获得带有六个连续立体中心的具有生物学意义的完全取代的六氢氧杂蒽酮。和出色的立体选择性(高达 10 : 1 dr 和 >99% ee)。换句话说,该反应在一锅操作中有效地产生了三个化学键和多达六个邻位立体中心。特别是,据我们所知,这是一种不对称的有机催化策略,能够在非螺环六氢氧杂蒽酮骨架上首次构建六个邻位立体中心。