ChemInform Abstract: Synthesis of Bis(indolyl)methanes Catalyzed by Triethylborane.

Abstract

Synthesis of Bis(indolyl)methanes Catalyzed by Triethylborane. -(GARCIA MERINOS*, J. P.; LOPEZ RUIZ, H.; LOPEZ, Y.; ROJAS LIMA, S.; Lett. Org. Chem. 12 (2015) 5, 332-336, http://dx.doi.org/10.2174/1570178612666150220225335 ; Area Acad. Quim., Univ. Auton. Estado Hidalgo, 42184 Hidalgo, Mex.; Eng.) -A. Forchert 40-138

Degenerative xanthate transfer to olefins under visible-light photocatalysis

“…Peroxide initiators such as dilauroyl peroxide (DLP) are commonly utilized [1–14], while decomposition of DLP needs a high reaction temperature and inevitably generates considerable amounts of byproducts derived from DLP that sometimes require tedious purification of the desired products. A combination of triethylborane (Et 3 B) and molecular oxygen can also initiate the reaction at lower temperature (e.g., room temperature), while the employment of Et 3 B is hampered due to its pyrophoric nature under aerobic conditions as well as undesired Et 3 B-mediated dexanthylation of α-xanthyl ketones [17–21]. As an alternative strategy, a light-driven approach has been developed [22–26], since the first degenerative transfer of xanthates using S -benzoyl O -ethyl xanthate as a photo-cleavable initiator under tungsten lamp irradiation was reported by Zard [25–26] (Scheme 1).…”

Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

“…On the other hand, boron‐based Lewis acids as catalysts have been widely employed in various reactions . Notably, boron can selectively catalyze the reduction of carboxylic acid to aldehyde, as well as Friedel–Crafts alkylation of an indole with aldehyde to BIM . Inspired by these precedents, it is envisioned that a Lewis acid catalyst might mediate reductive alkylation of indoles with carboxylic acids to obtain BIMs through stringing both selective reduction of carboxylic acid and C−C coupling together.…”