Acceleration effect of mild organocatalytic system 2,2′-biphenol/B(OH)₃ for 2-aza-Cope rearrangement

Organocatalysis by the combination of weak acids, namely, 2,2′-biphenol and B(OH)₃, for 2-aza-Cope rearrangement is described. Aldehydes and 1,1-diphenyl homoallylamine were converted into the corresponding homoallylamines in moderate-to-high yield in the presence of 10 mol% 2,2′-biphenol and 30 mol% B(OH)₃. In contrast to the conventional 2-aza-Cope rearrangement catalyzed by strong activators, a user- and environment-friendly organocatalytic system was established using a combination of inexpensive, easy-to-handle, non-hazardous, and bench-stable reagents.