Direct Synthesis ofN-Arylquinone Imine Acetals and Quinol Imines from Acetals
摘要:
In the absence of any added acidic catalyst quinone acetals as well as simple ketone and aldehyde acetals react with a variety of substituted anilines to form imines [Eq. (a)]. Contrary to what is expected from arguments based on their nucleophilicity, the most reactive anilines are those bearing electron-withdrawing groups.
formation of acetone dimethylacetal take place as revealed by NMR spectra of the solutions. The H–D exchange reaction is favored by electron-releasing ring substituents and yet is considerably slower than the rates of the E–Z isomerization of the corresponding imines. The carbinolamine ethers are formed when the substituents are strongly electronegative. Formation of acetone dimethylacetal occurs additionally