A new synthetic approach to 6-unsubstituted phenanthridine and phenanthridine-like compounds under mild and metal-free conditions

Abstract

A new and mild synthetic approach for the synthesis of 6-unsubstituted phenanthridine and phenanthridine-like compounds under metal-free conditions at room temperature has been developed. The strategy involved a tandem azide rearrangement/intramolecular annulation and oxidation reactions of biarylmethyl azide precursors to obtain the desired products in up to 99% yields with high regioselectivity.

Boroquinol Complexes with Fused Extended Aromatic Backbones: Synthesis and Optical Properties

“…According to this method, we first reacted 2‐aminobiaryl 1 a and salicylaldehyde 2 to thienoquinoline 4 a (Scheme and Table , entry 1) under similar conditions (PhMe, 20 % TFA, 100 °C). Apart from the desired product 4 a (59 %), substantial amounts of dearylated thienoquinoline 6 a (29 %) have been formed. Furthermore, through the analysis of the crude reaction mixture by 1 H NMR spectroscopy and ultraperformance liquid chromatography (UPLC)‐MS, phenol 7 has been identified as another byproduct.…”

“…Biaryls 1a-d were then reacted with aldehydes 2 or 3 under the optimized reaction conditions (PhMe, TFA, O 2 ,1 00 8C), giving the ligands 4a-d in 52-76 %y ield. Reactions in air showed the discussed dearylation fora ll systemsw ith yields of 15-17% for 6a-d [21,29] and lower yields of the desired ligands 4a-d in comparisont ot hose obtained under the optimized conditions With the optimized procedure, as ystem with five annulated rings and two N,O-chelating moieties was accessible (Scheme4). Phenylenediamine 15 was synthesized by Suzuki-Miyaura cross-coupling (see the Supporting Information) and subsequently reactedw ith aldehydes 2 or 3 under the abovementioned optimized conditions (PhMe, TFA, O 2 )t oa fford 17 in 46 %y ield.…”

Recent Advances in Reactions of Azides

“…As shown in Scheme , the synthesis of 6‐unsubstituted phenanthridine and phenanthridine‐like compounds under metal‐free conditions has been developed . The strategy involved a cascade TfOH‐promoted rearrangement/intramolecular annulation and oxidation reaction of biarylmethyl azide precursors to obtain the desired products with high regioselectivity.…”

Cascade C–C and C–N Bond Formation: A Straightforward Synthesis of Phenanthridines and Fused Quinol­ines

“…Thieno[2,3‐ c ]quinoline (3r): 21 Compound 3r was prepared according to the general experimental procedure as above, yield 0.159 g (86 %); white solid; m.p. 86–87 °C.…”