Three or Four Heteroatoms including at least One Boron

TLDR: In this paper, the authors describe various aspects of five-membered heterocyclic compounds containing one or more boron atoms, such as the procedures available for the preparation of these molecules, the reactivity of the heteroatoms (B, N, O, etc.) in the ring, the reactionivity of substituents attached to ring heterooms such as B−H, B−C, B-X, B·Si, B•Cu, etc.

Abstract: There has been an exponential increase in the synthesis and usage of a number of organic and inorganic boron compounds in the industry and academia. One of the important protocols for the synthesis of the organoboranes involves the hydroboration of olefins. This reaction is one of the most influential discoveries of the twentieth century in the field of organic synthesis. The organoboranes can be readily transformed into functional groups such as alcohols, amines, aldehydes, ketones, carboxylic acids, etc. The discovery of asymmetric versions of these reactions has added further impetus to the growing field of boron chemistry. This chapter describes various aspects of five-membered heterocyclic compounds containing one or more boron atoms, such as the procedures available for the preparation of these molecules, the reactivity of the heteroatoms (B, N, O, etc.) in the ring, the reactivity of substituents attached to ring heteroatoms such as B–H, B–C, B–X, B–Si, B–Cu, etc. The reactions have been categorized based on the reaction center; for example, the reactions of B–H, namely hydroboration of alkenes, asymmetric reduction of ketones, borylation and dehydrogenative borylation, etc., have been placed in a subcategory. Transition metal-catalyzed cross-couplings, stereoselective C–C bond-forming reactions such as allylation, Diels–Alder reaction, cycloadditions, and radical conjugate additions are among the key reactions that describe the reactivity of B–C bond. Several key transformations of B–X, B–Si, and B–Cu have also been dealt with in great detail. Apart from the reactivity, the ring syntheses from cyclic and acyclic compounds, and the syntheses of particular classes of compounds containing multiple heteroatoms have also been described in this chapter. Finally, some of the important compounds and their applications have been described at the end.