High-energy precursors can provide access to highly labile reactive intermediates, enabling unprecedented transformations under mild conditions. This review highlights a series of hypervalent λ³-haloganes, focusing on the λ³-iodanyl, λ³-bromanyl, and λ³-chloranyl groups as hypernucleofugic leaving groups. We also summarize recent studies on the generation and chemical reactivity of diatomic carbon (C₂) and m-benzyne, which can be best described as highly stabilized singlet biradicals.

Emil Fischer was a pioneer in peptide chemistry, striving to elucidate the chemical nature of peptides and proteins. In 1901, he and his colleague published the first paper on the subject. Since then, peptide chemistry has advanced steadily to the point that it is now possible to synthesize polypeptides, including enzymes. In addition, chemical synthesis is flexible and not constrained by the limitations of protein biosynthetic systems. Thus, proteins with various modifications, including post-translational modifications, can be synthesized. Current protein synthesis uses peptide thioesters synthesized by solid-phase methods as building blocks. This review will explain why peptide thioesters are utilized as building blocks for polypeptide synthesis and discuss the evolution of thioester preparation methods, as well as their applications in protein synthesis.

Red adzuki beans (Vigna angularis) are primarily used in producing sweet an-paste for use in Japanese confectionery, where the quality of the an-paste is evaluated based on its purple color. Catechinopyranocyanidins A and B (cpcA and cpcB) are seed coat pigments and might be responsible for the purple color of an-paste, thus, analyzing them in an-paste is crucial. However, no quantitative analyses of these compounds in an-paste have been reported. We examined extraction conditions for cpcA and cpcB from an-paste and established a quantitative analytical method. Additionally, we developed a pre-vacuum processing procedure for preparing purple an-paste. The more purple the an-paste was, the higher the content of cpcA and cpcB extracted from it. The purple color of an-paste originated from the catechinopyranocyanidins eluted from the seed coats upon boiling. Using the proposed procedure, we prepared more intensely purple wet sarashi-an compared with that generated via a conventional procedure.