Anthranils: versatile building blocks in the construction of C–N bonds and N-heterocycles

Abstract

This review article provides an overview of the recent progress in the transformations of anthranils, which have emerged as versatile building blocks in the assembly of various C–N bonds and medicinally active heterocyclic systems.

Competing Intra‐ vs Intermolecular Nitrene Transfer in the [Au]‐Catalysed Reaction of 2‐Alkynylphenylazides

“…Heating the reaction mixture at 80 °C increased the yield but not to a greater extent (35%, Table 1, entry 2). With the AuCl/Pd-complex/PtCl 2 , there was either a decrease in the yield or a complex mixture formation (Table 1, entries [3][4][5]. Next, the use of PPh 3 AuCl/AgSbF 6 as the catalyst improved the yield of 6 aa to 50% (Table 1, entry 6).…”

“…Methoxyphenyl)-3H-indol-3-ylidene)amino)benzaldehyde (4 ja): R f = 0.5 (15% EtOAc in petroleum ether); yield: 57 mg (83%); red solid; IR (neat)ν max 2925, 1696, 1256, 1169, 750 cm À 1 ; 1 H NMR (400 MHz, CDCl 3 ): δ 3.89 (s, 3H),6.39 (d, J = 7.5 Hz, 1H),6.85 (td, J = 7.5, 1.1 Hz, 1H), 6.97-7.04 (m, 3H), 7.29-7.52 (m, 3H), 7.61-7.69 (m, 1H), 8.02 (dd, J = 7.9, 1.3 Hz, 1H), 8.44-8.54 (m, 2H), 10.19 (s, 1H) ppm; NMR (100 MHz, CDCl 3 ): δ 55 4. (q), 114.0 (d, 2C), 118.1 (d), 121.4 (d), 121.5 (s), 124.3 (s), 124.4 (s), 125.5 (d), 125.6 (d), 126.5 (d), 129.3 (d), 131.8 (d, 2C), 134.0 (d), 135.2 (d), 152.4 (s), 158.5 (s), 162.4 (s), 165.1 (s), 166.2 (s), 189.6 (d) ppm; HRMS (ESI) calcd.…”

Gold‐Catalysed Nitroalkyne Cycloisomerization – Synthetic Utility

“…[22] This A successful intermolecular trapping of intermediate α-oxo gold carbene in this nitroalkyne cycloisomerization, especially one that leads to anthranils, has been documented recently from our group. [23] We speculated that in the presence of a nitrogen donor such as benzo[c]isoxazole (anthranil) 58 (which is an established nitrogen donor to metal coordinated alkynes and results in a α-oxo/imino gold carbene and also participates in carbene transfer reactions from the gold carbenes with equal ease [24] ) the intermediate α-oxo carbene that results during the cycloisomerization of nitroalkyne 57 should transfer the carbene to nitrogen (in competition with the original internal 6π-electron cyclization) to form an intermediate imine. Subsequent Davis-Beirut cyclization would lead to 3-acyl-(2formylphenyl)-2H-indazoles 59 (Scheme 16).…”

Metal‐Free Synthesis of Anthranils by PhIO Mediated Heterocyclization of ortho‐Carbonyl Anilines

“…Anthranils also serve as good substrates for [4+3] cycloaddition reactions with 1,3‐dipolar compounds yielding benzazepine and benzodiazepine derivatives (Figure 1f–g) or [4+2] cycloaddition with dienophiles to construct benzoxazinone, quinoline scaffolds and rutaecarpine, an antiplatelet inhibitor (Figure 1h–j) [3a–d] . In addition to diverse synthetic utility of anthranils, they exhibit potent biological activity (Figure 2).…”