Baker's yeast mediated reduction of dihydroxyacetone derivatives
摘要:
Several monoprotected dihydroxyacetone derivatives 4a-d and their acetates 5a-d were prepared and subjected to biotransformation with baker's yeast. The simple chemical modification of the substrates (i.e. transforming the relatively small hydrophilic hydroxymethyl group into a larger hydrophobic acetoxymethyl moiety) inverted the sense of enantiotope selectivity of these reductions yielding optically active diols 6a-d, or their enantiomeric acetates (7a-d) and diols (ent-6a-d), respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.
I<sub>2</sub>-Catalyzed Regioselective Oxo- and Hydroxy-acyloxylation of Alkenes and Enol Ethers: A Facile Access to α-Acyloxyketones, Esters, and Diol Derivatives
作者:Rambabu N. Reddi、Pragati K. Prasad、Arumugam Sudalai
DOI:10.1021/ol5027393
日期:2014.11.7
I-2-catalyzed oxo-acyloxylation of alkenes and enol ethers with carboxylic acids providing for the high yield synthesis of a-acyloxyketones and esters is described. This unprecedented regioselective oxidative process employs TBHP and Et3N in stoichiometric amounts under metal-free conditions in DMSO as solvent. Additionally, I-2-catalysis allows the direct hydroxy-acyloxylation of alkenes with the sequential addition of BH3 center dot SMe2 leading to monoprotected diol derivatives in excellent yields.
Neighboring Carbonyl Group Assisted Oxyacetoxylation of Propargylic Carboxylates with Retention of Chirality under Metal Free Condition
作者:Tapas R. Pradhan、Debendra K. Mohapatra
DOI:10.1002/adsc.201900314
日期:2019.8.5
reaction proceeds through the intramolecular nucleophilic attack of the neighboring carbonyl group on an alkynyliodonium intermediate. The process is general with broad substrate scope and is amenable for application to a variety of propargyl carboxylates including those obtained from naturalproducts. Insight into the mechanistic pathway by isotopic labelling (using H2O18 and D2O) and controlled experiments
提出了保留手性的伯,仲和叔炔丙基羧酸的无金属氧乙酰氧基化方法。该反应通过烷基炔酮中间体上相邻羰基的分子内亲核攻击而进行。该方法是一般的,具有广泛的底物范围,并且适用于包括从天然产物获得的那些炔丙基羧酸酯。通过同位素标记(使用H 2 O 18和D 2 O)洞察机械途径,并确认了对照实验。
Baker's yeast mediated reduction of dihydroxyacetone derivatives
Several monoprotected dihydroxyacetone derivatives 4a-d and their acetates 5a-d were prepared and subjected to biotransformation with baker's yeast. The simple chemical modification of the substrates (i.e. transforming the relatively small hydrophilic hydroxymethyl group into a larger hydrophobic acetoxymethyl moiety) inverted the sense of enantiotope selectivity of these reductions yielding optically active diols 6a-d, or their enantiomeric acetates (7a-d) and diols (ent-6a-d), respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.