Microwave-accelerated reductive amination between ketones and ammonium acetate

Exploring the mechanism of the reductive amination of acetophenones via the Borch approach: the role of the acid catalyst

The energetic viability of several mechanistic variations of the reductive amination of acetophenones via the Borch approach was re-examined through density functional theory calculations. The crucial involvement of the acid catalyst is evident not only in the elimination of water, but also in the initial nucleophilic step. This role increases with the electron-donating capability of the substituent positioned at the para-position of acetophenone.

A Convenient Synthesis of (16S,20S)-3β-Hydroxy-5α-pregnane-20,16-carbolactam and Its N-alkyl Derivatives

A concise synthesis of (16S,20S)-3β-hydroxy-5α-pregnane-20,16-carbolactam from tigogenin via the corresponding lactone is described. The most efficient synthetic route consisted of the lactone ring-opening with aminoalane reagent followed by PDC or Dess-Martin oxidation. The oxo-amide obtained was subjected to cyclization with Et₃SiH/TFA or Et₃SiH/Bi(TfO)₃. Alternately, the lactone was converted first to the oxo-acid, which was then subjected to the microwave-assisted reductive amination. N-Alkyl derivatives were also obtained in a similar way.

Synthesis of ring-substituted N-benzyl γ-phenyl GABA derivatives via reductive amination

Background: GABA derivatives are important for the development of drugs for disorders of the CNS and PNS. Results: We describe a simple synthesis of N-benzyl γ-phenyl-γ-aminobutyric acids, via the reductive amination of the corresponding γ-keto acids with benzylamines using ammonia borane. Conclusion: This procedure provides an efficient and economical method for the synthesis of GABA derivatives.