Visible-Light-Induced Dearomative Annulation of Indoles toward Stereoselective Formation of Fused- and Spiro Indolines.

Dearomatization approaches are attractive for their abilities to transform simple, planar arenes into complex, three-dimensional architectures. In particular, visible-light driven dearomatization strategies are significant because of their mild, green, and sustainable nature, enabling the fabrication of new chemical bonds via an electron transfer or energy transfer process. Indole compounds, being potentially bioactive and readily accessible, can be employed efficiently as building blocks for constructing diverse annulated frameworks under photocatalysis.

Annulations involving 1-indanones to access fused- and spiro frameworks.

Indanones are prominent motifs found in number of natural products and pharmaceuticals. Particularly, 1-indanones occupy important niche in chemical landscape due to their easy accessibility and versatile reactivity. In the past few years, significant advancement has been achieved regarding cyclization of 1-indanone core.

Stereoselective synthesis of fused-, spiro- and bridged heterocycles cyclization of isoquinolinium salts: a recent update.

Isoquinoline and its derivatives are ubiquitous in natural alkaloids, synthetic materials and pharmaceuticals with a broad spectrum of biological activities. In particular, isoquinolinium salts are important in organic synthesis because they can serve as building blocks for the rapid construction of various condensed heterocyclic systems involving cyclization processes. This review highlights novel stereoselective strategies that emerged in the last few years (2014-2021) for the synthesis of various fused-, spiro- and bridged heterocycles exploiting bench-stable or generated isoquinolinium salts.

Recent applications of ninhydrin in multicomponent reactions.

Ninhydrin (1,2,3-indanetrione hydrate) has a remarkable breadth in different fields, including organic chemistry, biochemistry, analytical chemistry and the forensic sciences. For the past several years, it has been considered an important building block in organic synthesis. Therefore, there is increasing interest in ninhydrin-based multicomponent reactions to rapidly build versatile scaffolds.

Synthesis and fluorescent properties of a new class of heterocycles of isoindole fused imidazoles with phenolic subunits.

A new class of heterocycles of isoindole fused imidazoles with phenolic subunits has been readily synthesized by a two-step one-pot reaction. In aprotic solvent they show high fluorescent properties (Phi(F) up to 0.93), but in protic polar solvent fluorescent intensity decreases.