Electrophilically activated nitroalkanes in the synthesis of 6,7-dihydro-1H-cyclopenta[g]perimidines

Electrophilically Activated Nitroalkanes in Synthesis of 3,4-Dihydroquinozalines

“…These phosphorylated nitronates tend to react with various carbon-based nucleophiles, for instance electron-rich arenes, allowing for Friedel-Crafts-type C-H functionalization reactions, often with subsequent accompanying rearrangements [21][22][23][24]. Furthermore, it was found that nitrogen-based nucleophiles (6), such as aliphatic amines [25][26][27], anilines [28][29][30][31], or hydrazines [32,33], can be utilized instead of water in a process mechanistically related to the classical Nef reaction [34][35][36]. Employing strategically placed second nucleophilic functionality (carbon or heteroatom-based), the resulting amidinium species (7) can be transformed into a variety of heterocyclic compounds, such as benzoxazoles (8) [23,28] or benzimidazoles (9) [28], perimidines (10) [29], 6,7-dihydro-1H-cyclopenta[gh]perimidines (11) [31], 1,3,4-oxa-di-azoles (12) [32,33], imidazolines (13) [25], 3,4-dihydro-iso-quinolines (14) [27], imidazo [1,5-a]pyridines (15) [26], and [1,2,4]triazolo [4,3-a] It occurred to us that a similar strategy can be applied for the straightforward preparation of 3,4-dihydroquinazolines as well.…”

Electrophilically activated nitroalkanes in reaction with aliphatic diamines en route to imidazolines

“…[17][18][19] The utilization of nucleophilic amines was also demonstrated. [20][21][22][23][24] Mechanistically, the latter process is related to the classical Nef reaction, [25][26][27] employing aniline [20][21][22][23] or hydrazine 24 species 8 instead of water. It was proposed, that this reaction initially provides imidinium ion 9, that can be further employed as a convenient building block for the synthesis of heterocyclic Scheme 1 Formation of imidazolines.…”

“…compounds: benzoxazoles 10, benzimidazoles 11, diazines 12-13, [20][21][22][23] and oxadiazoles 14 (ref. 24) (Scheme 2).…”

A nitroalkane-based approach to one-pot three-component synthesis of isocryptolepine and its analogs with potent anti-cancer activities

“…Mechanistically, this process is related to the classical Nef reaction, 7 employing nucleophilic amine species instead of water. We have discovered a number of innovative one-pot transformations involving nitrogen 8 or carbon 9 nucleophile-based versions of the Nef reaction and wondered if nitroalkane species 9, electrophilically activated by PPA, could serve as an alternative acylating agent to trigger cyclization of the in situ generated intermediate 5 into indoloquinoline species 1. Indeed, a nucleophilic attack of indole 5 across the C N bond of the phosphorylated nitronate 10 would afford (azanediylbis(oxy))bis(phosphonic) species 11, which after 1,2-elimination of ortho -phosphoric acid would produce O -phosphorylated oxime 12 ( Scheme 3 ).…”