One‐pot Cascade Reaction for the Synthesis of Phenanthridines via Suzuki Coupling/C−H Oxidation/Aromatization

Abstract

A one-pot cascade coupling/annulation reaction for the synthesis of phenanthridines has been developed from arylboronic acids and o-bromo arylamides with DMSO as a carbon source. The desired phenanthridines were obtained in moderate to good yields by using simple procedure.

Synthesis of Aza[n]helicenes (n = 4–7) via Photocyclodehydrochlorination of 1-Chloro-N-aryl-2-naphthamides

“…mp 103−104 °C (lit. 74 7-Aza [5]helicene (15b). GP4 was followed with 8-chloro-7aza [5]helicene (13b) (45 mg, 0.143 mmol, 1 equiv), NaOAc (14 mg, 0.171 mmol, 1.2 equiv), 5 mL of ethanol, 5 mL of toluene, and catalyst (10% Pd/C) (5 mg, 4.7 μmol Pd).…”

“…mp 100−101 °C) 1. H NMR (400 MHz, CDCl 3 ) δ 9.36 (s, 1H), 9.25−9.19 (m, 1H), 9.12 (d, J = 8.3 Hz, 1H), 8.34 (dd, J = 8.1, 1.5 Hz, 1H), 8.12−8.07 (m, 1H), 8.04 (d, J = 8.5 Hz, 1H), 7.96 (d, J = 8.5 Hz, 1H), 7.85−7.72 (m, 4H) (in agreement with data published in the literature74 ).…”

Recent Advances in DMSO-Based Direct Synthesis of Heterocycles

“…Pd(OAc) 2 was employed to catalyze the Suzuki reaction delivering biaryls. K 2 S 2 O 8 was applied as the activator of DMSO to generate meth(methylene)sulfonium, which was used for the formation of a third cycle in the presence of a copper catalyst ( Scheme 9 ) [ 23 ]. The electrocyclization of in situ-formed imine could be an efficient way of constructing fused rings.…”

I2-Catalyzed Three-Component Consecutive Reaction for the Synthesis of 3-Aroylimidazo[1,2-a]-N-Heterocycles

“…Despite these findings, developing a convenient method is still desirable in hit-to-lead drug discovery, which requires quick follow-up to construct 3-aroylimidazo­[1,2- a ]­pyridines from readily accessible and inexpensive starting materials in a single operation under mild conditions. Continuing our efforts to develop methods for constructing heterocycles and inspired by previous reports that used dimethyl sulfoxide (DMSO) as a one-carbon synthon (Scheme C), here we would like to describe the one-pot synthesis of 3-aroylimidazo­[1,2- a ]- N -heterocycles from aryl ketones and 2-amino- N -heterocycles using the DMSO/K 2 S 2 O 8 system catalyzed by I 2 (Scheme D).…”