8-R-5,7-Dinitroquinolines in [3+2] cycloaddition reactions with N-methylazomethine ylide

Pest und Geschrei in Dosen?

“…First, we studied 8‐R‐substituted 5,7‐dinitroquinolines in the reactions with unstabilized azomethine ylides to determine the influence of the R substituent on the process. The starting 8‐substituted quinolines were synthesized from readily available 8‐chloro‐5,7‐dinitroquinoline (see ref 16. and references cited therein; Scheme ).…”

“…Apparently, the cycloaddition proceeded regioselectively at the aromatic C5‐C6 bond, which was activated by the nitro group, followed by the elimination of HNO 2 and re‐aromatization of the benzene ring 16. The C7‐C8 bond was probably incapable of undergoing the cycloaddition because of the steric effects from the substituent at the 8‐position.…”

“…The reactions of 8‐methoxy‐ and 8‐phenoxy‐5,7‐dinitroquinolines ( 4 a and 4 b , respectively) with azomethine ylide 1 a proceeded in a different manner (Scheme ). According to the 1 H NMR spectroscopic data,16 the major product was compound 5 , and cycloaddition product 6 was also formed in trace amounts. It seems clear that in this case the rate of the cycloaddition was much lower than the rate of the nucleophilic substitution of the OR group under the action of dimethylamine, which was proven to be present in the reaction mixture 18.…”

Synthesis and Facile Dearomatization of Highly Electrophilic Nitroisoxazolo[4,3-b]pyridines

“…At the same time, dearomatization as a method of converting accessible, cheap, and simple aromatic compounds into more saturated, inaccessible and promising intermediates of greater molecular complexity is a very important approach in modern organic chemistry [36,37]. This work is part of our ongoing research on highly electrophilic systems and the application of the dearomatization strategy in the synthesis of new polyfunctional azaheterocycles [38][39][40][41][42][43][44][45][46][47][48]. We have previously shown that nitropyridines fused with π-deficient heterocycles (furoxan A, selenadiazole B), Scheme 1, react with neutral nucleophiles with the formation of 1,4-addition productsdihydropyridine derivatives [45,46,48].…”

Synthesis of Pyrido[2, 3‐a]phenoxazines and Pyrido[2, 3‐a]phenothiazines via Successive SNAr Processes

“…In the course of our studies of nitroquinolines chemistry, recently we have found that 5,7‐dinitroquinoline 1 and its N‐oxide react with thiols and NaN 3 giving the products of selective nucleophilic substitution of 5‐NO 2 , Scheme . In addition, the nucleophilic substitution of 8‐chlorine in 8‐chloro‐5,7‐dinitroquinoline 2 is well‐documented (see for example refs ,.…”