Metal-free synthesis of 1,4-benzodiazepines and quinazolinones from hexafluoroisopropyl 2-aminobenzoates at room temperature

Abstract

A metal-free synthesis of 1,4-benzodiazepines and quinazolinones from hexafluoroisopropyl 2-aminobenzoates has been developed at room temperature.

Synthesis of Benzotriazepin-1-ones via Decarboxylative [4 + 3]-Annulation of Isatoic Anhydrides with Nitrile Imines

“…In order to gain further insight into the reaction mechanism, we attempted a stepwise synthesis starting from isatoic anhydride 1a and hydrazonoyl chloride 2a (Scheme ). The reaction between isatoic anhydride 1a and HFIP in the presence of DMAP (10 mol %) resulted in the synthesis of HFIP-ester aniline 4 with a yield of 72% . In the presence of pyridine, the [4 + 3] annulation reaction between 4a and hydrazonoyl chloride 2a could be successfully carried out in HFIP, yielding the desired benzotriazepinone product 3aa with a yield of 78%.…”

Metal‐Free Cascade 1,4‐Conjugate Addition/Selective Annulation Strategy for Divergent Synthesis of Polysubstituted Imidazoles and 4‐Alkenylquinazolines

“…To further improve the outcome, several of the common solvents were screened and none of them showed better results (Table 1, entries [11][12][13][14][15][16][17]. To establish the optimal reaction conditions, further screening was carried out (Table 1, entries [18][19][20][21][22] and the best optimized condition was found to be the utilization of 2 a (2.0 equiv.) in DCE at 120 °C under air atmosphere for 12 h (Table 1, entry 19).…”

“…On the basis of the experimental results and literature reports, [19] a plausible mechanism was proposed as depicted in Scheme 4. Initially, the deamination of propargylamine 1 a or 4 a generates the alkynyl o-quinone methide (o-AQM) intermediate under thermal conditions as proposed in the previous literature.…”

Aza‐oxyallyl Cations and Their Applications in (3+m) Cycloaddition Reactions

“…Later Chen et al. (2021) reported the same reactivity of aza‐oxyallyl cation with isatoic anhydride with significant improvement in reaction conditions [51b] . They have used NEt 3 as the base for decarboxylative addition of HFIP to isatoic anhydride A with the subsequent reaction of aza‐oxyallyl cation to generate hexafluoroisopropyl 2‐aminobenzoates B , which undergoes intramolecular cyclization in DMF at room temperature to furnish a wide range of 1,4‐ benzodiazepines 106 .…”