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 β‐Naphthols

Abstract Chiral phosphoric acid‐catalyzed couplings of C ‐alkynyl N,N′ ‐di‐( tert ‐butoxycarbonyl)‐aminals with β ‐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 β ‐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.