N-Boc-aminals as easily accessible precursors for less accessible N-Boc-imines: facile synthesis of optically active propargylamine derivatives using Mannich-type reactions
We developed a facile and practical synthesis of N-Boc-aminals, which can be used as precursors for less accessible N-Boc-imines. Aminals were obtained via simple dehydration condensation reactions of t-butyl carbamate (BocNH2) and various aldehydes in acetic anhydride, followed by filtration and washing with hexane. The obtained N-Boc-alkynylaminals could be successfully applied in enantioselective
Crafty aminals: The in situgeneration of hitherto unattainable alkynyl‐substituted N‐Boc‐protected imines was realized by the acid‐catalyzed elimination of tert‐butyl carbamate from N‐Boc aminals. A wide variety of N‐Boc imines can be generated, which can then be utilized for subsequent carbon–carbon bond‐forming reactions, such as Mannich‐type reactions.