Cobalt(II) chloride catalyzed acylation of alcohols with acetic anhydride: scope and mechanism
摘要:
Cobalt(II) chloride catalyzes the acetylation of a variety of alcohols with acetic anhydride in excellent yield. Primary hydroxyl groups can be selectively acylated in the presence of secondary and tertiary ones while the secondary hydroxyl groups can be preferentially acetylated in the presence of tertiary ones. Tertiary alcohols have been found to give ketones, acetoacetates, olefins, and diketene in addition to the acetate. The beta-hydroxy esters and ketones can be acylated under these conditions without any elimination, and this reaction has been compared with 4-(dimethylamino)pyridine (DMAP)-mediated acylations where elimination of the resulting beta-acetoxy carbonyl compound is observed. A detailed investigation of the acylation of tertiary alcohols has revealed that these reactions proceed via a tertiary alkoxy radical and ketene. A mechanism for these acylations is proposed by invoking an electron-transfer process.
One-Pot Preparation of Alcohols from Aromatic Olefins and Acrylic Acid Derivatives by Cobalt(II) Porphyrin-Catalyzed Reductive Oxygenation Followed by Reduction with Trimethyl Phosphite
acid derivatives were converted to benzyl alcohols and α-hydroxyalkanoic acid derivatives in good yields by the reductive oxygenation with oxygen and triethylsilane in the presence of a catalytic amount of cobalt(II) porphyrin followed by treating the reaction mixture with trimethyl phosphite.
在催化量的钴 (II) 卟啉存在下,通过氧和三乙基硅烷的还原氧化,各种芳族烯烃和丙烯酸衍生物以良好的收率转化为苯甲醇和 α-羟基链烷酸衍生物,然后用三甲基卟啉处理反应混合物。亚磷酸盐。
Expanding the Substrate Specificity of <i>Thermoanaerobacter pseudoethanolicus</i>
Secondary Alcohol Dehydrogenase by a Dual Site Mutation
作者:Musa M. Musa、Odey Bsharat、Ibrahim Karume、Claire Vieille、Masateru Takahashi、Samir M. Hamdan
DOI:10.1002/ejoc.201701351
日期:2018.2.14
The authors acknowledge the support provided by the Deanship of Scientific Research (DSR) at King Fahd University of Petroleum and Minerals (KFUPM) for funding this work under project number IN151032. They also acknowledge the supported by baseline research fund to S.M.H. by King Abdullah University of Science and Technology.
Scandium trifluoromethanesulfonate is a useful Lewis acid catalyst for cleavage of acetates containing coordinative groups adjacent to the acetyl carbonyl. The reaction proceeds under weak acidic conditions at room temperature. Racemizable alpha-keto acyloxy compounds are deacetylated without racemization. Selective mono-deacetylation at the 10-position of paclitaxel has been achieved. (C) 1999 Elsevier Science Ltd. All rights reserved.