Synthesis of Chiral Propargylamines, Chiral 1,2-Dihydronaphtho[2,1-b]furans and Naphtho[2,1-b]furans with C-Alkynyl N,N'-di-(tert-butoxycarbonyl)-aminals and ß-Naphthols.

Chiral phosphoric acid-catalyzed couplings of C-alkynyl N,N'-di-(tert-butoxycarbonyl)-aminals with ß-naphthols led to chiral propargylamines in moderate to high yields with high to excellent enantioselectivity, in which the reactions underwent sequential chiral phosphoric acid-catalyzed in situ formation of N-(tert-butoxycarbonyl)-imines (N-Boc-imines) from the aminals, and 1,2-addition of ß-naphthols to the N-Boc-imines. Chiral 1,2-dihydronaphtho[2,1-b]furans and naphtho[2,1-b]furans were prepared with satisfactory results when 10 mol% AgOAc and 20 mol% 2,6-lutidine or 1.2 equiv. of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were added to the resulting chiral propargylamines solution, respectively.

Chemo-, Regio-, and Stereoselective Construction of Core Skeleton of Furo[2,3-b]pyrrole via Multicomponent Bicyclization Reaction.

An efficient and straightforward N-ethyldiisopropylamine (DIPEA)-catalyzed multicomponent bicyclization reaction was developed to synthesize furo[2,3-b]pyrrole derivatives from ß-ketothioamides, glyoxals, and ethyl cyanacetate in EtOH at rt for 1.5 h. This was achieved via a sequential Knoevenagel condensation, Michael addition, and double cyclization, resulting in continuous formation of four chemical bonds (two C-C, two C-O, and one C-N bonds), two five-membered cycles, and three stereogenic centers in a one-pot operation.

Direct Construction of 2-Aryliminochromenes from Arynes, N,S-Keteneacetals, and DMF.

A concise and direct synthetic strategy for the construction of 2-aryliminochromene skeleton by cascade three-component coupling reaction of arynes, N,S-keteneacetals, and DMF in good yields has been disclosed. The process demonstrates the first example of aryne chemistry combined with N,S-keteneacetals. Using this strategy, an expeditious synthesis of biologically important arylimino-2H-chromene-3- carboxamides was achieved.

Organocatalytic Atroposelective Construction of Axially Chiral N-Aryl Benzimidazoles Involving Carbon-Carbon Bond Cleavage.

Axially chiral compounds widely occur in natural products, biologically active molecules, ligands, and catalysts, and their efficient and enantioselective synthesis is highly desirable. Herein, we report a novel method for the atroposelective construction of axially chiral N-aryl benzimidazoles with chiral phosphoric acid as the organocatalyst via reaction of N1-(aryl)benzene-1,2-diamines with multicarbonyl compounds. The present method provided the target products in high yields (up to 89%) with excellent enantioselectivity (up to 98% ee).