立体障害エーテルおよび複雑なエーテルのアクセス法
Sumit Pareek1, Pavan Mandadi1, Someswara Rao Sanapala1
1Department of Chemistry, Indian Institute of Technology Tirupati, Yerpedu 517619, India.
Abstract:
We report an efficient metal-free and scalable reductive etherification method to synthesize hindered ethers using chlorodimethylsilane (CDMS) and catalytic Schreiner thiourea. The reaction relies on in situ generated HCl and thiourea via anion-binding catalysis, activating carbonyls to form an oxocarbenium intermediate and enabling hydride transfer to create an ether bond. A broad substrate scope (89 substrates) and excellent functional group tolerance including complex ethers of steroids, terpenoids, peptides, and late-stage ritonavir modification have been demonstrated for this method.
さらに関連する動画
06:31Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
Published on: November 27, 2015
08:12A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
関連する概念動画
02:29Ethers from Alcohols: Alcohol Dehydration and Williamson Ether Synthesis
Ethers can be prepared from organic compounds by various methods. Some of them are discussed below,
Preparation of Ethers by Alcohol Dehydration
In this method, in the presence of protic acids, alcohol dehydrates to produce alkenes and ethers under different conditions. For example, in the presence of sulphuric acid, dehydration of ethanol at 413 K yields ethoxyethane, whereas it yields ethene at 443 K.
02:28Structure and Nomenclature of Ethers
Ethers are organic compounds with an ether functional group which is characterized by an oxygen atom connected to two — identical or different — alkyl, aryl, or vinyl groups. The C–O–C linkage in dimethyl ether — the simplest ether — has an approximately tetrahedral bond angle of 110.3 degrees. The oxygen atom is sp3- hybridized, with the C–O distance being about 140 pm.
Classification of Ethers
Based on their attached substituent...
02:35Ethers from Alkenes: Alcohol Addition and Alkoxymercuration-Demercuration
Ethers can also be prepared from alkenes through acid-catalyzed addition of alcohols and alkoxymercuration–demercuration.
Preparation of Ethers by Acid-Catalyzed Addition of Alcohol to Alkenes
The acid-catalyzed addition of alcohol to an alkene involves treating the alkene with an excess of alcohol in the presence of an acid catalyst to form an ether under suitable conditions. The hydrogen will add to the less substituted carbon so that the nucleophile can attack the more substituted...
02:18Ethers to Alkyl Halides: Acidic Cleavage
02:17Physical Properties of Ethers
An ether molecule has a net dipole moment due to the polarity of C–O bonds. Subsequently, boiling points of ethers are lower than those of alcohols of comparable molecular weight and slightly higher than those of hydrocarbons of comparable molecular weight (Table 1).
Ethers can act as hydrogen bond acceptors, making them more water-soluble than hydrocarbons, but since ethers cannot act as hydrogen bond donors, they are much less soluble in water than alcohols. Ethers are considered...
02:23Autoxidation of Ethers to Peroxides and Hydroperoxides