DMSO methylates a broad range of amines in the presence of formic acid, providing a novel, green and practical method for aminemethylation. The protocol also allows the one‐pot transformation of aromatic nitro compounds into dimethylated amines in the presence of a simple iron catalyst.
Synthesis of Tetrahydroquinolines via Borrowing Hydrogen Methodology Using a Manganese PN<sup>3</sup> Pincer Catalyst
作者:Natalie Hofmann、Leonard Homberg、Kai C. Hultzsch
DOI:10.1021/acs.orglett.0c02905
日期:2020.10.16
simple secondary alcohols is reported. This one-pot cascade reaction is based on the borrowinghydrogenmethodology promoted by a manganese(I) PN3 pincer complex. The reaction selectively leads to 1,2,3,4-tetrahydroquinolines thanks to a targeted choice of base. This strategy provides an atom-efficient pathway with water as the only byproduct. In addition, no further reducing agents are required.
products 20–22, together with the intramolecular CH insertion product with an intact cyclopropyl ring 19. On the basis of these observations, we concluded that the intramolecular CH insertion of the nitrene proceeds primarily by the hydrogen abstraction–recombination mechanism. We propose, however, a small contribution of the concerted mechanism to the intramolecular CH insertion, based on the solvent dependence
In buffered water, a broad range of quinoline derivatives underwent asymmetrictransferhydrogenation in air with the rhodium catalyst 1 and sodium formate as the hydrogen source to furnish synthetically important 1,2,3,4‐tetrahydroquinolines with excellent enantioselectivities (see scheme; R=H, Me, F, Cl, Br, OMe; R′=alkyl, aryl).
在缓冲水中,各种各样的喹啉衍生物在空气中以铑催化剂1和甲酸钠作为氢源进行不对称转移加氢,以提供具有重要对映选择性的重要合成1,2,3,4-四氢喹啉(参见方案; R = H,Me,F,Cl,Br,OMe; R'=烷基,芳基)。
Manganese-catalyzed asymmetric transfer hydrogenation of quinolines in water using ammonia borane as a hydrogen source
of manganese-catalyzed asymmetric transfer hydrogenation of N-heteroaromatics in water is reported. This ATH reaction proceeds smoothly without the need for inert atmosphere protection in the presence of a water-stable manganese catalyst, which bears an easily available aminobenzimidazole ligand. Ammonia borane, regarded as a green, cheap and high atom economical hydrogensource, was applied. Various
报道了锰催化 N-杂芳烃在水中不对称转移氢化的第一个例子。该 ATH 反应在水稳定的锰催化剂存在下顺利进行,无需惰性气氛保护,该催化剂带有易于获得的氨基苯并咪唑配体。氨硼烷被认为是一种绿色、廉价、高原子经济的氢源。各种喹啉以高产率转化为所需产品,对映体过量 (ee) 高达 99%。当前方案的实用性通过将其应用于汉考克生物碱 (−)-cuspareine 的克级全合成来证明,总产率为 96%。