Gold(I)‐Catalyzed Ring Expansion of Alkynylcyclopropyl Allyl Ethers to Construct Tetrasubstituted Methylenecyclobutanones: A Mechanistic Investigation about the Character of Catalytic Amount of Water
mechanism has been proposed on the basis of deuterium and 18O‐labeling experiments, Mass spectroscopic analysis, 1H and 13Cnuclearmagneticresonance (NMR) spectroscopic tracking and density functional theory (DFT) calculations. The further transformation of these methylenecyclobutanones into polycyclic skeleton has been realized by a practical three‐step synthetic procedure. Several other transformations
Regioselectivity Switch: Gold(I)-Catalyzed Oxidative Rearrangement of Propargyl Alcohols to 1,3-Diketones
作者:A. Stephen K. Hashmi、Tao Wang、Shuai Shi、Matthias Rudolph
DOI:10.1021/jo301381z
日期:2012.9.7
The gold(I)-catalyzed oxidative rearrangement of propargyl alcohols provides an efficient and selective route to 1,3-diketones under mild conditions. Pyridine-N-oxides were used as external oxidants with, different from related substrates, no alkylidenecycloalkanones or oxetan-3-ones formed as side-products.
Ir-Catalyzed Asymmetric Hydrogenation of α-Alkylidene β-Lactams and Cyclobutanones
作者:Jingzhao Xia、Yu Nie、Guoqiang Yang、Yangang Liu、Ilya D. Gridnev、Wanbin Zhang
DOI:10.1002/cjoc.201800088
日期:2018.7
Chiral β‐lactams and cyclobutanones are present in numerous natural and pharmaceutical products. The stereoselective construction of chiral four‐membered cyclic compounds is an ongoing challenge for the chemical community. Herein, we report a highly stereocontrolled construction of four‐membered ring (mini‐sized) β‐lactams and cyclobutanones via an Ir/In‐BiphPHOX‐catalyzed asymmetric hydrogenation
许多天然和药物产品中都存在手性β-内酰胺和环丁酮。手性四元环化合物的立体选择性结构是化学界面临的挑战。本文中,我们报告了通过Ir / In-BiphPHOX催化的不对称加氢对四元环(微型)β-内酰胺和环丁酮进行高度立体控制的结构,从而提供了相应的旋光四元环羰基产物,这些产物带有α-手性碳中心,在温和的反应条件下(1.0-2.5 bar H 2)具有出色的收率(高达99%)和对映选择性(高达98%)持续1.0-10小时)。该反应代表了广泛的底物范围。还进行了催化产物的多种转化,以显示该方案的潜在效用。
Ruthenium-catalysed synthesis of chiral exocyclic allylic alcohols <i>via</i> chemoselective transfer hydrogenation of 2-arylidene cycloalkanones
exclusive asymmetric reduction of CO bonds of 2-arylidene four-, five-, six-, and seven-membered cycloalkanones has been studied systematically. The asymmetric transfer hydrogenation was performed using a robust and commercially available chiral diamine-derived ruthenium complex as a catalyst and HCOOH/Et3N as a hydrogen source under mild conditions, giving 51 examples of chiral exocyclic allylic alcohols
已经系统地研究了2-芳基四,五,六和七元环烷烃的C O键的排他不对称还原。在温和条件下,使用稳固且可商购的手性二胺衍生钌络合物作为催化剂,HCOOH / Et 3 N作为氢源,进行不对称转移氢化,给出了51种示例手性环外烯丙基醇,收率高达96%, 99%ee。该方法也适用于抗炎洛索洛芬和天然产物(-)-goniomitine的活性中间体的克级合成。
Facile synthesis of 2-methylenecyclobutanones via Ca(OH)<sub>2</sub>-catalyzed direct condensation of cyclobutanone with aldehydes and (PhSe)<sub>2</sub>-catalyzed Baeyer–Villiger oxidation to 4-methylenebutanolides
(2-MCBones), used to be difficult to access, but can now be easily achieved by a green and stereospecific Ca(OH)2-catalyzed direct and simple aldol condensation of cyclobutanone and aldehydes under mild conditions. The obtained (E)-2-MCBones should be a class of potentially useful building blocks in synthesis as they could readily undergo an interesting (PhSe)2-catalyzed Baeyer–Villiger (BV) oxidation
2-亚甲基环丁酮(2-MCBones)过去很难获得,但现在可以通过在绿色和立体定向Ca(OH)2催化下在温和条件下环丁酮和醛的直接简单的羟醛缩合直接实现。所获得的(E)-2-MCBones应该是一类在合成中潜在有用的结构单元,因为它们在室温下很容易通过H 2 O 2进行有趣的(PhSe)2催化的Bayerer -Villiger(BV)氧化而得到通用的4-亚甲基丁醇化物。机理研究表明,BV反应最有可能通过苯硒代过氧苯甲酸酐[PhSe(O)O] 2的初步形成而进行。O然后转化为苯硒酸过氧酸PhSe(O)OOH作为活性氧化剂,然后将其选择性添加到2-MCBones的C O键中,然后进行选择性的C-C键裂解和重排,得到4-亚甲基丁醇化物。