Janthinoid A, an unprecedented tri-nor-meroterpenoid with highly modified bridged 4a,1-(epoxymethano)phenanthrene scaffold, produced by the endophyte of Penicillium janthinellum TE-43

Janthinoid A (1), an unprecedented C22 meroterpenoid featuring a highly modified bridged 4a,1-(epoxymethano)phenanthrene scaffold incorporating eight continuous quaternary carbons, along with its biosynthetic-related C25 analogue andrastone I (2), were isolated...

Iron-catalyzed oxidative bis-arylation of indolin-2-ones for direct construction of quaternary carbons

The cross-dehydrogenative coupling protocol is catalyzed by a simple iron salt, and air is used as the terminal oxidant under very mild conditions, offering a novel synthetic method for the direct construction of all-carbon quaternary centers.

Lewis Acid Mediated Cyclization: Synthesis of 2-Spirocyclohexylindolines Bearing Vicinal Quaternary Carbons

Herein, we report the synthesis of 2-spirocyclohexylindolines based on a Lewis acid mediated cyclization. This diastereoselective procedure provides the target structrues in a straightforward way via dual activation.

Contiguous Quaternary Carbons: A Selection of Total Syntheses

Contiguous quaternary carbons in terpene natural products remain a major challenge in total synthesis. Synthetic strategies to overcome this challenge will be a pivotal prerequisite to the medicinal application of natural products and their analogs or derivatives. In this review, we cover syntheses of natural products that exhibit a dense assembly of quaternary carbons and whose syntheses were uncompleted until recently. While discussing their syntheses, we not only cover the most recent total syntheses but also provide an update on the status quo of modern syntheses of complex natural products. Herein, we review (±)-canataxpropellane, (+)-waihoensene, (–)-illisimonin A and (±)-11-O-debenzoyltashironin as prominent examples of natural products bearing contiguous quaternary carbons.