The Formation of Seven-Membered Heterocycles under Mild Pictet–Spengler Conditions: A Route to Pyrazolo[3,4]benzodiazepines Timothy A. Katte Tristan A. Reekie William T. Jorgensen Michael Kassiou 10.1021/acs.joc.6b00710.s001 https://acs.figshare.com/articles/journal_contribution/The_Formation_of_Seven_Membered_Heterocycles_under_Mild_Pictet_Spengler_Conditions_A_Route_to_Pyrazolo_3_4_benzodiazepines/3380227 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%. 2016-05-09 00:00:00 ketone Heterocycle Reported trifluoroacetic acid Formation aldehyde Pyrazolo method synthesis heterocycle Pictet acetic acid condensation Mild High substrate scope