Nitration and Cyclization of Arene-Alkynes: An Access to 9-Nitrophenathrenes

Abstract

A nitration and cyclization of arene-alkynes has been developed, affording 9-nitrophenathrenes efficiently. This reaction probably proceeds via addition of the nitrogen dioxide to the alkyne moiety, intramolecular radical addition of vinyl radical to one aryl ring, oxidation of radical intermediate into carbocation species, and elimination of a proton. In this transformation, Fe(NO) was used as both nitro source and oxidant.

Radical annulation of a designed diene system: access to nitro-benzo[b]azepines

“…These results reveal that this transformation may proceed via a radical pathway. Based on the above experimental results and previous literature reports about the AgNO 3 /K 2 S 2 O 8 combination, 11,15 a plausible mechanism for this transformation was proposed.…”

“…8 As nitration is a fundamental process for the introduction of a nitro group (−NO 2 ) into organic molecules, 9 recently, the radical addition cyclizations of O 2 N˙ to unsaturated bonds has grown as a practical strategy for the synthesis of nitro-containing 5- or 6-membered N -heterocycles (Scheme 1a). 10,11 However, an elegant synthetic strategy for 7-membered nitro-heterocycles remains a formidable challenge, mainly due to their instability, nonbonding interaction, and the entropy factor. Continuing our particular interest in nitrogen heterocyclic chemistry, 12 we designed a diene system ( N -allyl-2-(1-phenylvinyl)-aniline derivatives), and wondered whether a novel radical cyclization reaction via chemo- and regioselective O 2 N˙ addition and 7- endo cyclization processes might be achieved to construct important 7-membered azepine derivatives (Scheme 1b).…”

Copper‐Catalyzed Diphenylation of P(O)‐OH Bonds with Cyclic Diaryliodonium Salts

“…We further performed a large‐scale reaction of [1,1′‐ biphenyl]‐2,2′‐iodonium triflate ( 1 a , 6 mmol) with diphenyl phosphinic acid ( 2 a , 5 mmol) and afforded 3 a in 91 % yield (2.255 g) (Scheme ). In the presence of Pd(PPh 3 ) 4 , CuI and Et 3 N, 3 a could react efficiently with 3‐ethynyl aniline to afford 2′‐((3‐aminophenyl)ethynyl)‐[1,1′‐biphenyl]‐2‐yl diphenyl phosphinate ( 6 ) in 75 % yield . In addition, we further performed the reaction of 3 a with styrene via the catalysis of palladium in the presence of a stoichiometric amount of silver, and the expected product ( 8 ) was obtained in 83 % yield .…”

Persulfate-nitrogen doped graphene mixture as an oxidant for the synthesis of 3-nitro-4-aryl-2H-chromen-2-ones from aryl alkynoate esters and nitrite

“…Liu et al , for example, utilized aryl alkynoate esters as radical receptors and Fe(NO 3 ) 3 as the nitro-radical source for the synthesis of 3-nitro-4-arylcoumarins in nitromethane at 100 °C in 2018 (Scheme 1a). 7 Sau et al , last year, also used aryl alkynoate esters as precursors and tert -butyl nitrite (TBN) as a source of NO radicals to synthesize 3-nitro-4-arylcoumarins in DMSO at 120 °C (Scheme 1b). 8 Despite having had various levels of success, both of these procedures (Scheme 1a and b) have limitations of high reaction temperatures (100–120 °C) and hazardous volatile organic solvents.…”