In contrast to the borrowing hydrogen-type N-alkylation reactions, in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the addition of external aldehydes was accidentally found to be a simple and effective protocol for alcohol activation. This interesting finding subsequently led to an efficient and green, practical and scalable aldehyde-catalyzed transition metal-free dehydrative N-alkylation method for a variety of amides, amines, and alcohols. Mechanistic studies revealed that this reaction most possibly proceeds via a simple but interesting transition metal-free relay race mechanism.

http://onlinelibrary.wiley.com/doi/10.1002/adsc.201200881/full