Gold Salts as Alternative Catalysts in Promoting Cascade Condensation of 2-Aminobenzaldehydes with Alcohols and Amines

J Org Chem. 2024 Nov 15;89(22):16828-16837. doi: 10.1021/acs.joc.4c02162. Epub 2024 Oct 30.

Abstract

The distinctive features of gold self-relay catalysts were alternatively utilized in the intriguing cascade condensation of 2-aminobenzaldehydes with alcohols and amines. Using NaAuCl4·2H2O as a catalyst, a range of 13-alkyloxy-7,11b-dihydro-6H,13H-6,12-[1,2]benzenoquinazolino[3,4-a]quinazoline derivatives was produced in good to high yields through A3B condensation of various 2-aminobenzaldehydes with alcohols. By carefully choosing the reaction conditions, gold catalysis also proved effective for A2B condensation with primary aryl- and benzylamines, facilitating the synthesis of challenging McGeachin bisaminals, including a chiral nonracemic derivative of 2-(S)-methylbenzylamine. The mild conditions of this gold-catalyzed approach may lead to new advancements in the field.