Enantioselective Synthesis of Binaphthol Derivatives by Oxidative Coupling of Naphthol Derivatives Catalyzed by Chiral Diamine·Copper Complexes
作者:Makoto Nakajima、Irie Miyoshi、Kumiko Kanayama、Shun-ichi Hashimoto、Masahiro Noji、Kenji Koga
DOI:10.1021/jo981808t
日期:1999.4.1
A highly efficient process of aerobic oxidative coupling of 2-naphthol derivatives catalyzed by 1 mol % of Cu(OH)Cl.TMEDA has been developed, Enantioselective oxidative coupling of naphthols was achieved by the use of 10 mol % of chiral catalysts prepared from proline-derived diamines and cuprous chloride, affording the corresponding binaphthols in good enantioselectivities of up to 78% ee. The ester moiety at the 3-position of the substrate was found to be essential for the good asymmetric induction observed in the present coupling reaction.
CAL-B-mediated efficient synthesis of a set of valuable amides by direct amidation of phenoxy- and aryl-propionic acids
efficient, easy and sustainable amidation of a set of non-activated carboxylic acids with anilines, assisted by CAL-B, as biodegradable catalyst, is reported. The enzymatic amidation reactions are performed on set of nonsteroidal anti-inflammatory drugs (NSAIDs), phenoxypropionic acid and protected-prolines by direct condensation of one equivalent of carboxylic acids and two equivalents of anilines
The Stability of Imidazolidinones is the Primary Influence on the Catalytic Activity of Proline Amides and Proline Sulfonamides in Enamine Catalysis Using Alkyl Aldehyde Substrates
作者:Sergey Tin、José A. Fuentes、Tomas Lebl、Matthew L. Clarke
DOI:10.1002/ejoc.201201174
日期:2013.1
catalyst) forms high concentrations of enamine that is only slowly (days) converted into a single diastereomer of an inert imidazolidinone. In contrast, another good catalyst, a prolinesulfonamide, immediately forms a reactive imidazolidinone, that rapidly ring-opens and exchanges with other aldehydes. This presumably drip-feeds iminium ions and enamines into the catalytic cycle. Thus, there are two quite
一些 N 取代的脯氨酸衍生物催化烷基醛与亲电伙伴的反应,而其他的则产生可忽略不计的产物。已经研究了醛和脯氨酸衍生物之间的关键反应,并提出了观察到的反应性的基本原理。源自芳香胺(不良催化剂)的简单脯氨酸酰胺以烯胺为代价非常迅速地形成稳定的咪唑烷酮,后者被检测到,如果有的话,不到一个小时。碱性较低的脯氨酸酰胺形成咪唑烷酮的动力学非对映异构体,非常缓慢地反转其立体化学以产生最终的热力学产物。这些非对映体的立体化学完全由 1H NMR、NOE 和 TOCSY 实验确定。源自烷基胺(良好催化剂)的脯氨酸酰胺形成高浓度的烯胺,该烯胺仅缓慢(数天)转化为惰性咪唑啉酮的单一非对映异构体。相比之下,另一种良好的催化剂,脯氨酸磺酰胺,会立即形成反应性咪唑啉酮,迅速开环并与其他醛交换。这大概是将亚胺离子和烯胺滴入催化循环中。因此,有两种完全不同的机制导致有效的催化。这些机械见解现在应该允许对使用醛的烯胺反应进行