A divergent strategy is presented for the synthesis of 1,3-di- and 1,3,4-trisubstituted β-carbolines through an unprecedented one-pot triple-orthogonal-metal relay catalysis, and 1,3-disubstituted 4-hydroxy-β-carbolines through a one-pot bimetallic relay catalysis from readily accessible 3-(2-aminophenyl)-5-hexenyn-3-ols. These strategies were elaborated to enable the synthesis of benzofuro[2,3-c]pyridines, benzothieno[2,3-c]pyridines, and isoquinolines, which otherwise require multistep synthesis.

Diversity oriented one-pot synthesis of cyclohepta[b]indoles, indolotropones, and tetrahydrocarbazoles (THCs) have been reported. Readily accessible 3-(2-aminophenyl)-5-hexenyn-3-ols under a one-pot trimetallic orthogonal catalysis furnish tetrahydrocyclohepta[b]indoles, and a one-pot quadruple reaction sequence of the enynols generates dihydrocyclohepta[b]indoles and indolotropones. During this study, formation of THCs was realized to be a reason for the yield loss in certain cases, this observation led to the development of a one-pot bimetallic approach for the synthesis of 1,3-disubstituted THCs.

A series of unexpected reactions triggered by the dimethyloxosulfonium methylide led to the discovery of unconventional approaches for the synthesis of cyclopropafused tetralones and indeno-spirocyclopropanes. These highly functionalized structures were further elaborated in one step to privileged scaffolds such as tetralones, indenones, and fluorenones. As a whole, the results presented herein establish new diversity-oriented folding pathways.

Desymmetrization-based protocols for the synthesis of highly functionalized indeno-spirocyclopropanes and cyclopropa-fused indanes have been established through unexpectedr eactions triggered by the Corey-Chaykovsky reagent. These structures were further elaborated in one step to privileged scaffolds such as fluorenones, indenones, and naphthaphenones. For instance, an acid-catalyzedt ransformation of indeno-spirocyclopropanes provided fluorenones via ah omo-Nazarov-type cyclization, and naphthaphenones were obtained via an acidcatalyzed cyclopropane ring-opening/retro-Michael sequence.Cyclopropanes are important structural units presenti ns everal bioactive natural productsa nd pharmaceutically relevant compounds including af ew marketed drugs (Figure 1). [1] Medicinal chemists take advantage of the enhanced metabolic stability and conformational rigidity offered by cyclopropanes during drug design and development. [2] In addition, the strained Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

A variety of cyclopropyl aryl ketones undergo uncatalyzed cascade ring-opening/recyclization reactions to generate indenones and fluorenones. In addition, a new strategy to access 3-hydroxyindanones possessing two contiguous stereogenic centers, one of them being an all-carbon quaternary center, was also established. During the course of the investigation, pronounced solvent, temperature, and substituent effects on the product distribution were discovered.