Gold(I)-Catalyzed Cycloisomerization-Indole Addition Cascade: Synthesis of 3(2H)-Furanone-Incorporated Unsymmetrical 3,3'- Bis(indolyl)methanes

Short Total Synthesis of (+)-Colletotryptins B-D and Mucronatin B Derivative

The short and first total synthesis of (+)-colletotryptins B-D, ent-colletotryptin A, and diastereomer of mucronatin B, which are a group of natural 3-(indol-2-yl)-3-(indol-3-yl)-1,2-propanediol (IIPDO) analogues containing two stereogenic centers at the C8' and C9' positions, isolated from endophytic fungus Colletotrichum sp. SC1355 and Tetrapterys mucronata, respectively, has been successfully accomplished in two and three steps with overall yields ranging from 28 to 54%. Key features of this synthesis include an innovative Bi(OTf)3-catalyzed stereoselective transindolylation of (S)-3,3'-di(1H-indol-3-yl)propane-1,2-diol. The operational simplicity, environmentally friendly catalyst, and broad functional group tolerance of this modular strategy render it suitable for adoption in both academic and industrial settings.

Unlocking Diversity: From Simple to Cutting-Edge Synthetic Methodologies of Bis(indolyl)methanes

From a synthetic perspective, bis(indolyl)methanes have undergone extensive investigation over the past two to three decades owing to their remarkable pharmacological activities, encompassing anticancer, antimicrobial, antioxidant, and antiinflammatory properties. These highly desirable attributes have spurred significant interest within the scientific community, leading to the development of various synthetic strategies that are not only more efficient but also ecofriendly. This synthesis-based literature review delves into the advancements made in the past 5 years, focusing on the synthesis of symmetrical as well as unsymmetrical bis(indolyl)methanes. The review encompasses a wide array of methods, ranging from well-established techniques to more unconventional and innovative approaches. Furthermore, it highlights the exploration of various substrates, encompassing readily available chemicals such as indole, aldehydes/ketones, indolyl methanols, etc. as well as the use of some specific compounds as starting materials to achieve the synthesis of this invaluable molecule. By encapsulating the latest developments in this field, this review provides insights into the expanding horizons of bis(indolyl)methane synthesis.

Divergent synthesis of difluoromethylated indole-3-carbinols, bisindolylmethanes and indole-3-methanamines

Indole-3-carbinol, bisindolylmethanes (BIMs) and indole-3-methanamines exhibit diverse therapeutic activities. Fluorinated molecules are widely used in pharmaceuticals. Herein we report a facile and straightforward method for the successful synthesis of difluoromethylated indole-3-carbinols, bisindolylmethanes and indole-3-methanamines by a Friedel-Crafts reaction. The reaction involves the in situ generation of difluoroacetaldehyde from difluoroacetaldehyde ethyl hemiacetal in the presence of a base or an acid. This protocol is distinguished by its good to excellent yields, broad substrate compatibility, good functional group tolerance and scalability.

Ag(I)-catalyzed dearomatizing spirocyclization/nucleophile addition cascade reactions of indole-tethered ynones

Ag(I)-catalyzed highly diastereoselective construction of divergent spiroindolines is disclosed herein. The approach proceeds via dearomatizing spirocyclization of indole-tethered ynones followed by C-nucleophile or hydride trapping. The established strategy is accompanied by the generation of two new C-C bonds and two contiguous stereocenters. This strategy features a broad range of (hetero)arenes as C-nucleophiles and excellent diastereoselectivity.

Divergent Synthesis of 3-Pyrrolidin-2-yl-1H-indoles, Symmetric and Unsymmetric Bis(Indolyl)Methanes (BIMs) through Photocatalyzed Decarboxylative Coupling/Friedel-Crafts Alkylation Reaction

This paper reports the acid-controlled divergent synthesis of 3-pyrrolidin-2-yl-1H-indoles and symmetric and unsymmetrical bis(indolyl)methanes (BIMs) through photocatalyzed decarboxylative coupling and Friedel-Crafts alkylation reactions, respectively. The protocol involves C-H functionalization, switching formation of two products, room-temperature conditions, low photocatalyst loadings, without strong oxidant, and moderate to excellent yields. This method has been applied for the synthesis of natural product vibrindole A and 1,1-bis(1H-indol-3-yl)-2-phenylethane.

Iodocycloisomerization/Nucleophile Addition Cascade Transformations of 1,2-Alkynediones

A general electrophilic iodocyclization/nucleophile addition cascade transformation for 1,2-alkynediones for the synthesis of various oxygen heterocycles and access to regioselective alkyne hydroxylation is reported. Furan-tethered ynediones resulted in the construction of exo-enol ethers via carbonyl-alkyne cyclization-initiated heteroarene dearomatization, whereas other (hetero)arene-, alkenyl-, and alkyl-tethered ynediones resulted in the formation of highly functionalized 3(2H)-furanones. Importantly, the developed domino protocols involve the construction of important heterocyclic scaffolds and installation of two functional groups in a single operation. Moreover, the use of water as a nucleophile resulted in regioselective alkyne hydroxylation via furanone ring opening. The developed protocols are characterized by a wide substrate scope, and their utility has been demonstrated by a number of postsynthetic transformations.