Highly selective oxidative cross-coupling of differently substituted 2-naphthols mediated by Cu(II)-tert-butyl amine complexes is described. The “cross”-products are obtained in good to excellent yields and the selectivity up to ⪢90% is observed depending on the substitution of naphthol nuclei. The alternative procedures - the cross-coupling of free naphthols with CuCl(OMe) as well as the coupling
Chiral α-Aminophosphonates as Ligands in Copper-Catalyzed Asymmetric Oxidative Coupling of 2-Naphthols
作者:Qian-Ming Zuo、Ming-Ying Wu、Li-Biao Han、Shang-Dong Yang
DOI:10.1021/acs.orglett.4c01582
日期:2024.6.28
stereogenic centers have been employed as ligands in the copper-catalyzed oxidative coupling of 2-naphthols, resulting in the production of chiral BINOLs in favorable yields and moderate to good enantiomericexcess. This represents the first application of chiral P-based ligands to enable such a transformation. The synthesis of these chiral α-aminophosphonate ligands offers a significant advantage over approaches
具有相邻碳和膦酸酯立体中心的手性 α-氨基膦酸酯已被用作铜催化 2-萘酚氧化偶联的配体,从而以良好的产率和中等至良好的对映体过量生产手性 BINOL。这代表了手性 P 基配体首次应用来实现这种转变。与通常需要复杂的合成工艺来生产手性配体的方法相比,这些手性 α-氨基膦酸酯配体的合成具有显着的优势。
Zn(OTf)<sub>2</sub>-Promoted Chemoselective Esterification of Hydroxyl Group Bearing Carboxylic Acids
作者:Narsimha Mamidi、Debasis Manna
DOI:10.1021/jo302502r
日期:2013.3.15
Selective esterification of aliphatic and aromatic carboxylic acids with various alcohols is studied using triphenylphosphine, I-2, and a catalytic amount of Zn(OTf)(2). Use of this catalyst allows the formation of esters at a faster rate with good to excellent yield by activating the in situ generated acyloxyphosphonium ion intermediate. During the esterification process, both their aromatic and aliphatic hydroxyl groups are fully preserved from trans-esterification. The results show that the bulkiness and the reactivity of this doubly activated intermediate III control the selectivity and the rate of the reaction, respectively. The method is also useful for direct amidation reactions.
Enantioselective Oxidative Coupling of 2-Naphthol Derivatives by Copper-(<i>R</i>)-1,1′-Binaphthyl-2,2′-diamine-TEMPO Catalyst
AbstractAn efficient chiral copper catalytic system [(R)‐(+)‐1,1′‐binaphthyl‐2,2′‐diamine‐copper(I) chloride‐TEMPO] for the asymmetric oxidative coupling of 2‐naphthol derivatives to synthesize enantiomerically enriched BINOL derivatives has been developed with good to excellent enantiomeric excess (up to 97% ee). The addition of a catalytic quantity of 2,2,6,6‐tetramethylpiperidin‐1‐yl oxyl (TEMPO) to the copper‐(R)‐(+)‐1,1′‐binaphthyl‐2,2′‐diamine complex greatly enhanced the reactivity and enantioselectivity of the enantioselective oxidative coupling of 2‐naphthol derivatives and also reduced the reaction temperature from 90 °C to room temperature in dichloromethane solvent.magnified image