Enzymatic synthesis of both enantiomeric forms of 3-allyloxy-propane-1,2-diol
摘要:
The stereoselective synthesis of (S)- and (R)-3-allyloxy-propane-1,2-diol has been accomplished in four steps from (RS)-3-allyloxy-propane-1,2-diol. Only one intermediate, namely 1-benzoyloxy-3-allyloxy-2-propanone has been prepared by a chemical reaction, that is, pyridinium chlorochromate oxidation of 1-benzoyloxy-3-allyloxypropan-2-ol. All of the remaining reactions (regioselective acylations, asymmetric bioreduction of prochiral ketones, and enzymatic alcoholysis) have been carried out in the presence of biocatalysts. (C) 2012 Elsevier Ltd. All rights reserved.
A green and convenient method for regioselective mono and multiple benzoylation of diols and polyols
摘要:
An efficient method for regioselective benzoylation of diols and polyols was developed. The benzoylation is catalyzed by only 0.2 equiv of benzoate anion in acetonitrile with the addition of a stoichiometric amount of benzoic anhydride under very mild condition, leading to high yields. Compared with all other methods, this method shows particular advantage in regioselective multiple benzoylation of polyols, and in avoiding the use of any metal-based catalysts and any amine bases, which is more environment friendly. (C) 2015 Elsevier Ltd. All rights reserved.
A novel metal-free organobase-catalyzed regioselective benzoylation of diols and carbohydrates has been developed. Treatment of diol and carbohydrate substrates with 1.1 equiv. of 1-benzoylimidazole and 0.2 equiv. of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in MeCN under mild conditions resulted in highly regioselective benzoylation for the primary hydroxyl group. Importantly, compared to most commonly
Fast Addition of s‐Block Organometallic Reagents to CO
<sub>2</sub>
‐Derived Cyclic Carbonates at Room Temperature, Under Air, and in 2‐Methyltetrahydrofuran
作者:David Elorriaga、Felipe Cruz‐Martínez、María Jesús Rodríguez‐Álvarez、Agustín Lara‐Sánchez、José Antonio Castro‐Osma、Joaquín García‐Álvarez
DOI:10.1002/cssc.202100262
日期:2021.5.6
straightforward synthesis of: highly substituted tertiary alcohols, β‐hydroxy esters, or symmetric ketones, working always under air and at room temperature. Finally, an unprecedented one‐pot/two‐step hybrid protocol is developed through combination of an Al‐catalyzed cycloaddition of CO2 and propylene oxide with the concomitant fast addition of RLi reagents to the in situ and transiently formed cyclic carbonate
Regioselective Sulfonylation/Acylation of Carbohydrates Catalyzed by FeCl<sub>3</sub> Combined with Benzoyltrifluoroacetone and Its Mechanism Study
作者:Jian Lv、Jia-Jia Zhu、Yu Liu、Hai Dong
DOI:10.1021/acs.joc.9b03128
日期:2020.3.6
A catalyticamount of FeCl3 combined with benzoyl trifluoroacetone (Hbtfa) (FeCl3/Hbtfa = 1/2) was used to catalyze sulfonylation/acylation of diols and polyols using diisopropylethylamine (DIPEA) or potassium carbonate (K2CO3) as a base. The catalytic system exhibited high catalytic activity, leading to excellent isolated yields of sulfonylation/acylation products with high regioselectivities. Mechanism
An inexpensive catalyst, Fe(acac)<sub>3</sub>, for regio/site-selective acylation of diols and carbohydrates containing a 1,2-<i>cis</i>-diol
作者:Jian Lv、Jian-Tao Ge、Tao Luo、Hai Dong
DOI:10.1039/c8gc00428e
日期:——
This work describes the [Fe(acac)3] (acac = acetylacetonate)-catalyzed, regio/site-selective acylation of 1,2- and 1,3-diols and glycosides containing a cis-vicinal diol. The iron(III) catalysts initially formed cyclic dioxolane-type intermediates with substrates between the iron(III) species and vicinal diols, and the efficient and selective acylation of one hydroxyl group was subsequently achieved
containing cis-vicinal diol, the substrate scope also includes glycosides without cis-vicinal diol. For such a substrate scope, usually, only methods using stoichiometric amounts of organotinreagents can lead to the same protection pattern with high selectivities and highly isolated yields (84–97% in most cases). Therefore, SnCl2, as a low toxicity and extremely cheap reagent, should be the best catalyst