Controlling diaza-Cope rearrangement reactions with resonance-assisted hydrogen bonds.
NMR studies reveal that the equilibrium between 1 and 2 lies essentially toward 1 to the left without any detectable amount of 2. DFT computation shows that the value of K1 is about 1.4 x 10-5, and X-ray crystal structures show that the resonance-assisted hydrogen bond (RAHB) in 1 (1.66 A) is shorter than the regular hydrogen bond in 2 (1.75 A). The enormous selectivity can be explained in terms of the strength of the RAHBs in 1 compared to that of the regular hydrogen bonds in 2.
Chin
Jik
J
Department of Chemistry, 80 St. George Street, Toronto M5S 3H6, Canada. jchin@chem.utoronto.ca
Mancin
Fabrizio
F
Thavarajah
Nirusha
N
Lee
Donghyung
D
Lough
Alan
A
Chung
Doo Soo
DS