First reported by Farnum as much as 40 years ago, diketopyrrolopyrroles (2,5‐dihydropyrrolo[4,3‐c]pyrrolo‐1,4‐diones) are currently one of the most widely used dyes, with applications that span high‐quality pigments, field‐effect transistors, bulk‐heterojunction solar cells, dye‐sensitized solar cells, and fluorescence imaging. Due to the breadth of their utility, there have been several focused reviews on this topic since 1988. Considering the growing importance of these dyes, this review describes the overall progress made in four decades in both synthesis and the elucidation of their reactivity, and offers a critical comparison of various methods reported in the literature. The relationship between their structure and optical properties is also reviewed in detail. The extension of diketopyrrolopyrroles' chromophore leads to a significant change in both linear and nonlinear optical properties. A very strong bathochromic shift in the absorption and an increase in the two‐photon absorption cross‐section are typical for these analogues. Straightforward synthesis combined with good stability and a near‐unity fluorescence quantum yield ensures that diketopyrrolopyrroles will continue to attract attention for years to come. The goal of this review is to systematize knowledge on these dyes, enabling their use in more real‐world applications.

Oxidative aromatic coupling occupies a fundamental place in the modern chemistry of aromatic compounds. It is a method of choice for the assembly of large and bewildering architectures. Considerable effort was also devoted to applications of the Scholl reaction for the synthesis of chiral biphenols and natural products. The ability to form biaryl linkages without any prefunctionalization provides an efficient pathway to many complex structures. Although the chemistry of this process is only now becoming fully understood, this reaction continues to both fascinate and challenge researchers. This is especially true for heterocoupling, that is, oxidative aromatic coupling with the chemoselective formation of a C−C bond between two different arenes. Analysis of the progress achieved in this field since 2013 reveals that many groups have contributed by pushing the boundary of structural possibilities, expanding into surface‐assisted (cyclo)dehydrogenation, and developing new reagents.

Synthesis, optical properties, and applications of various types of benzocoumarin compounds are overviewed.