Catalyst-controlled site-selective methylene C–H lactonization of dicarboxylic acids
作者:Hau Sun Sam Chan、Ji-Min Yang、Jin-Quan Yu
DOI:10.1126/science.abq3048
日期:2022.6.24
and γ-methylene carbon-hydrogen (C-H) bonds of free carboxylic acids is a long-standing challenge. Here we show that, with a pair of palladium catalysts assembled with quinoline-pyridone ligands of different chelate ring sizes, it is possible to perform highly site-selective monolactonization reactions with a wide range of dicarboxylicacids, generating structurally diverse and synthetically useful γ-
游离羧酸的β-和γ-亚甲基碳氢(CH)键的催化剂控制的位点选择性活化是一个长期存在的挑战。在这里,我们表明,通过一对由不同螯合环尺寸的喹啉-吡啶酮配体组装的钯催化剂,可以与多种二羧酸进行高度位点选择性的单内酯化反应,产生结构多样且合成上有用的γ-和δ-内酯通过位点选择性β-或γ-亚甲基CH活化。剩余的羧基可作为进一步合成应用的多功能关键,如从丰富的二羧酸中全合成两种天然产物 myrotheciumone A 和pedicellosine 所证明的那样。
The Development of the Surgical Treatment of Morbid Obesity
作者:Mervyn Deitel、Scott A. Shikora
DOI:10.1080/07315724.2002.10719237
日期:2002.10
Morbid obesity is defined as obesity with a body mass index greater than or equal to40, or greater than or equal to35 with secondary serious diseases. Conservative medical therapies in these individuals generally fail to sustain weight loss. Thus, surgical operations have evolved which are based on gastric restriction and/or malabsorption. Historically, the intestinal bypass operation was followed by the gastric bypass operation (in some instances combined with intestinal bypass) or by the gastric restriction operations (gastroplasty or gastric banding), Laparoscopic techniques are now being used for these operations, but require surgical expertise in both the bariatric operations and advanced laparoscopic skills. All operations may have complications, but these occur in a very small percent. Postoperative follow-up and nutritional surveillance are mandatory. The operations result in significant weight loss, and the current operations have a mean lasting weight loss of about 50 percent of excess body weight, with improvement or resolution of most obesity-associated conditions. There is evidence that even modest to moderate weight loss in these individuals has significant medical benefit.
Palladium(II)-catalyzed carboxylation reactions of olefins: scope and utility
作者:J. K. Stille、R. Divakaruni
DOI:10.1021/jo01334a006
日期:1979.9
Hueckel, Justus Liebigs Annalen der Chemie, 1938, vol. 533, p. 1,26
作者:Hueckel
DOI:——
日期:——
435. Alicyclic glycols. Part XVII. The decalin-2 : 3-diols