研究了在新型DIPSkewphos / 3-AMIQ-Ru II配合物的催化下芳族γ-和δ-酮酯的不对称氢化为旋光羟基酯或二醇。在最佳条件下(8 atm H 2 ,Ru络合物/ t- C 4 H 9 OK = 1:3.5,25°C),用97–99定量获得了γ-和δ-羟基酯(包括γ-内酯)。 % ee。当反应在某些苛刻的条件下(20 atm H 2 ,[ t -C 4 H 9 OK] = 50 m m,40°C)进行时,得到的1,4-二醇和1,5-二醇主要是95 –99% ee。酯基的反应性特别取决于底物的两个羰基部分之间的碳间隔基的长度。不论反应条件如何,β-和β-酮酸酯的反应选择性地提供羟基酯。该催化剂体系用于γ-ϵ-二酮二酯加氢成三羟基酯的对映选择性和区域选择性(对于两个酯基之一)。
hydroacylation reaction of alkenes has been achieved employing readily available carboxylicacids as the acyl source and hydrosilanes as a hydrogen source via photoredox catalysis. The combination of both single electron transfer and hydrogen atom transfer steps has dramatically expanded new applications of carboxylicacids in organic synthesis. The protocol also features extremely mild conditions, broad
Copper-Catalyzed Oxidative Cleavage of Electron-Rich Olefins in Water at Room Temperature
作者:Daniel J. Lippincott、Pedro J. Trejo-Soto、Fabrice Gallou、Bruce H. Lipshutz
DOI:10.1021/acs.orglett.8b01883
日期:2018.9.7
of electron-rich olefins into their corresponding carbonyl derivatives is described as an alternative to ozonolysis. The scope includes various precursors to arylketone derivatives, as well as oxidations of enol ethers bearing atypical alkyl and dialkyl substitution, the first of their kind among such metal catalyzed alkene cleavage reactions. The use of an inexpensive copper salt, room temperature
Tin-free radical alkylation of ketones viaN-silyloxy enamines
作者:Hyun-Ji Song、Che Jo Lim、Sunggi Lee、Sunggak Kim
DOI:10.1039/b606295d
日期:——
The radical alkylation of ketones is achieved by their conversion into corresponding N-silyloxy enamines, followed by a radical reaction with alkyl halides bearing electron-withdrawing groups.
Catalytic Redox Chain Ring Opening of Lactones with Quinones To Synthesize Quinone-Containing Carboxylic Acids
作者:Xiao-Long Xu、Zhi Li
DOI:10.1021/acs.orglett.9b01672
日期:2019.7.5
Catalytic ringopening of five- to eight-membered lactones with quinones is achieved through a redox chain mechanism. With low loading of a simple metal triflate Lewis acid catalyst and a chain initiator, C–H bonds of many quinones were efficiently functionalized with carboxylic acid-containing side chains. This method also features 100% atom economy and wide substrate scope. A novel route to the anti-asthma
Acyl Radicals from α-Keto Acids Using a Carbonyl Photocatalyst: Photoredox-Catalyzed Synthesis of Ketones
作者:Da-Liang Zhu、Qi Wu、David James Young、Hao Wang、Zhi-Gang Ren、Hong-Xi Li
DOI:10.1021/acs.orglett.0c02351
日期:2020.9.4
Acylradicals have been generated from α-keto acids using inexpensive and commercially available 2-chloro-thioxanthen-9-one as the photoredox catalyst under visible light illumination. These reactive species added to olefins or coupled with aryl halides via a bipyridyl-stabilized Ni(II) catalyst, enabling easy access to a diverse range of ketones. This reliable, atom-economical, and eco-friendly protocol