Domino reaction of 3-nitro-2-(trifluoromethyl)-2H-chromenes with 2-(1-phenylalkylidene)malononitriles: synthesis of functionalized 6-(trifluoromethyl)-6H-dibenzo[b,d]pyrans and a rare case of [1,5] sigmatropic shift of the nitro group

Understanding the molecular mechanism of γ‐elimination of nitrous acid in the framework of the molecular electron density theory

“…36 The global electron density transfer (GEDT) 27 to the BET. 34 For the BET studies, the corresponding reaction paths F I G U R E 1 Examples of beta-elimination of nitrous acid 4,5,[7][8][9][10][11] F I G U R E 2 A theoretically possible mechanism for the nitrous acid extrusion from furoxane functionalized nitrolic acids were followed by performing the topological analysis of the ELF for at least 181 nuclear configurations along the IRC paths. The ELF molecular geometries and basin attractor positions were visualized using the GaussView program.…”

“…The migration of the nitro group in reactions plays an important role in the processes of transformation of organic compounds. Within this class of reactions, besides the nitro group rearrangement realized via [1.3]‐ 1,2 or [1.5]‐sigmatropic shift mechanisms, 3–6 many examples of nitrous acid extrusion were described. Most of these reactions proceed according to the β‐elimination scheme.…”

“…Most of these reactions proceed according to the β‐elimination scheme. The molecular mechanism of this type of decompositions reactions has recently been a subject of systematic studies regarding β‐nitroalkyl sulfoxides, 7,8 β‐nitroalkyl carboxylates, 9 5‐nitroisoxazolidines, 10 Δ 2 ‐4‐nitroisoxazolines 11 as well as 3‐nitro‐2H‐chromene systems, 4,5 and other (Figure 1).…”

“…Examples of beta‐elimination of nitrous acid 4,5,7–11 …”

Nitroalkenes in the synthesis of carbocyclic compounds

“…When chromene 280 were used in the reaction with malononitrile derivatives 281 in the presence of Et 3 N, the corresponding CF 3 -containing functionalized 6H-dibenzo[b,d]pyrans 282 can be achieved in good to high yields (Scheme 93). 145 It is notable that the 3-nitro-2-(trichloromethyl)-2H-chromenes do not lead to any desired product. In the case of 2-(1-phenylpropylidene)malononitriles 281 (R 2 ¼ CH 3 ), the reaction proceeded in two steps with the formation of 7-amino-10-methyl-10-nitro-9-phenyl-6-(triuoromethyl)-10,10a-dihydro-6H-benzo- [c]chromene-8-carbonitriles (284), which were isolated as a result of a rare [1,5] 3-ethoxy-2-nitro-2-en-1-ones 286 (Scheme 94).…”