Zr-Catalyzed Synthesis of Tetrasubstituted 1,3-Diacylpyrroles from N-Acyl α-Aminoaldehydes and 1,3-Dicarbonyls

A Zr-catalyzed synthesis of tetrasubstituted 1,3-diacylpyrroles is reported that employs the direct use of N-acyl α-aminoaldehydes with 1,3-dicarbonyl compounds. The products were formed in up to 88% yield and shown to be hydrolytically and configurationally stable under the reaction conditions (THF/1,4-dioxane and H₂O). The N-acyl α-aminoaldehydes were readily prepared from the corresponding α-amino acids. The reaction tolerates a wide array of substrate types including alkyl-, aryl-, heteroaryl-, and heteroatom-containing groups on the aminoaldehyde side chain. A variety of 1,3-dicarbonyls proved amenable to the reaction along with an aldehyde derived from a l,l-dipeptide, an aldehyde generated in situ, and an N-acylated glucosamine.

One-Pot Synthesis of Monofunctionalized Oligoethylene Glycols through Ring-Opening and Heterogeneous Hydrolysis of Macrocyclic Sulfates

The one-pot nucleophilic ring-opening reaction of oligoethylene glycol macrocyclic sulfates provides an efficient strategy for the monofunctionalization of oligoethylene glycols without protecting or activating group manipulation. In this strategy, the hydrolysis process is generally promoted by sulfuric acid, which is hazardous, difficult to handle, environmentally unfriendly, and unfit for industrial operation. Here, we explored a convenient handling solid acid, Amberlyst-15, as a replacement for sulfuric acid to accomplish the hydrolysis of sulfate salt intermediates. With this method, 18 valuable oligoethylene glycol derivatives were prepared with high efficiency, and gram-scale applicability of this method has been successfully demonstrated to afford a clickable oligoethylene glycol derivative 1b and a valuable building block 1g for F-19 magnetic resonance imaging traceable biomaterial construction.

Manufacture of n-Propyl Propionate Using Ion Exchange Resins: Reaction Kinetics and Feasibility of Reactive Distillation

Reaction kinetics of esterification of propionic acid with 1-propanol to produce n-propyl propionate using Amberlyst-15 as a catalyst was investigated in this work. Effect of various parameters was studied. Initially, the efficacy of different catalysts was investigated which revealed that Amberlyst-15 can be suitably used for the reaction. This was followed by mass transfer exclusion which included effect of agitation speed, catalyst size and calculation of Weisz-Prater Criterion. Parameters selected for kinetic study were mole ratio of propionic acid to 1-propanol, temperature, catalyst loading and initial water concentration. Catalyst reusability was also verified. Aspen      Custom Modeler (ACM) was used to regress kinetic parameters and a good match was obtained. Reactive Distillation (RD) runs in the batch mode were performed which showed that RD is a better option for process intensification (PI) for this reaction. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).