The Formation of Seven-Membered Heterocycles under Mild Pictet-Spengler Conditions: A Route to Pyrazolo[3,4]benzodiazepines.

@article{Katte2016TheFO,
  title={The Formation of Seven-Membered Heterocycles under Mild Pictet-Spengler Conditions: A Route to Pyrazolo[3,4]benzodiazepines.},
  author={Timothy A Katte and Tristan A. Reekie and William T Jorgensen and Michael Kassiou},
  journal={The Journal of organic chemistry},
  year={2016},
  volume={81 11},
  pages={4883-9}
}
Reported is a method for the synthesis of seven-membered heterocycles via a Pictet-Spengler condensation reaction under very mild conditions. High substrate scope allows for use of aldehydes using catalytic amounts of acetic acid yielding 39-90% and ketones using catalytic amounts of trifluoroacetic acid yielding 25-83%.