Importance of Baylis-Hillman adducts in modern drug discovery

The Baylis-Hillman (BH) reaction plays a fascinating role in the field of synthetic and medicinal chemistry. BH adducts and their derivatives have been used as crucial synthons for the synthesis of various pharmaceutically useful natural products and compounds with carbocyclic or heterocyclic frameworks. This digest letter aims to discuss some key ideas for the synthesis of biologically active scaffolds using BH reaction and raise the awareness of this emerging research domain in modern drug discovery. In this review, we will present and discuss recent reports of various biologically active scaffolds derived from BH reaction, and their reported biological activities.     

Cu-Mn spinel oxide catalyzed regioselective halogenation of phenols and N-heteroarenes

A novel simple, mild chemo- and regioselective method has been developed for the halogenation of phenols using Cu-Mn spinel oxide as a catalyst and N-halosuccinimide as halogenating agent. In the presence of Cu-Mn spinel oxide B, both electron-withdrawing and electron-donating groups bearing phenols gave monohalogenated products in good to excellent yields with highest para-selectivity. The para-substituted phenol gave monohalogenated product with good yield and ortho-selectivity. N-Heteroarenes such as indoles and imidazoles also gave monohalogenated products with high selectivity. Unlike the copper-catalyzed halogenation, the present method works well with electron-withdrawing group bearing phenols and gives comparatively better yields and selectivity. The Cu-Mn spinel catalyst is robust and reused three times under optimized conditions without any loss in catalytic activity. Nonphenolics did not undergo this transformation.     

Carbonyl Compounds′ Journey to Amide Bond Formation

The formation of amide bonds is one of the most stimulating emerging areas in organic and medicinal chemistry. Amides are recognized as central building blocks in a plethora of interesting pharmaceuticals, proteins, peptides, polymers, natural products, functional materials, and biologically relevant carbocyclic or heterocyclic molecules, and they are also found in a variety of industrial fields. Therefore, a review of recent developments and challenges in the formation of amide bonds from carbonyl compounds is particularly important. Herein, we have scrutinized a range of metal‐catalyzed and metal‐free approaches for the synthesis of amides from aldehydes, ketones, and oximes. In addition, this Minireview highlights relevant mechanistic studies, as well as the potential applications of these methods in the synthesis of candidate drug molecules. We hope that the data compiled herein will encourage further progress in this notable area of chemistry research.