Bifunctional organocatalysts have remarkably advanced in organic chemistry owing to their high stability to moisture/air, relatively non-toxicity, ease of handling, and recoverability. Among chiral bifunctional organocatalysts, squaramides have emerged as the privileged catalyst in recent years. This review article proposes a comprehensive report on fine-tunable bifunctional chiral squaramide-catalyzed sulfa-Michael addition, which is based upon synchronous interplay of synergistic ‘electrophilicnucleophilic’ dual activation strategy via multiple H-bonding interactions for the construction of common and/or complex molecular entities bearing multiple stereocenters. Mechanistic discussions were kept only briefly, wherein significant understandings have been realized. The contribution of squaramide catalyst in the construction of C–S bond via sulfa-Michael addition has been amenable in medicinal, natural, and industrial chemistry. Attention has been paid to summarizing the progress made in chiral squaramide-catalyzed asymmetric sulfa-Michael addition and subsequent cascade/domino reaction sequences between 2011 and 2022.

Transition-metal nanoparticles-catalyzed C–H activation/functionalization is a prominent topic in contemporary research to functionalize privileged heterocyclic scaffolds which hold a significant space in scientific community with their immense applications in medicinal, natural product, agricultural chemistry, and materials science. Among transition-metal-based nanoparticles, Pd nanoparticle catalysis has emerged as the most attractive tool promoting a wide array of practical synthetic transformations of heterocycles. In the last few years, catalytic application of Pd nanoparticles in C–H functionalization has gained popularity in generating relatively inaccessible bonds with a high degree of selectivity and efficiency via the activation of surface metal atoms at nanoscale level. The quantum size effect of nanoparticles offers a large surface area, typically many easily accessible active sites/unit area. These unique characteristics of nanoparticles are considered primary factors of enhanced catalytic activity compared to bulk materials. The nanoparticles catalysts anchored on solid-supports plus unsupported type (e.g., magnetic nanoparticles) provide easy separation from reaction mixture allowing recyclability multiple times, which contributes notably to sustainable management and cost efficiency of a production process. In the current review, we aim to outline Pd nanoparticles-catalyzed C(sp2)–H arylation synthesizing functionalized heterocycles. The preparation of Pd nanoparticles and mechanistic realizations in the corresponding reactions have been explained briefly.