Notes- Cyclic Products from Hydrazines. I. Nitroindoles, Nitrotetrahydrocarbazoles, Nitroindolenines and Nitrotetrahydrocarbazolenines

Abstract

When 5.1 g. of I was redistilled after having been stored at 0°for 3 months, 4.9 g. (96%) of I, b.p. 69-71.5°was obtained and 0.1 g. of residue (2%) was left.Adduct of I with maleic anhydride. To 0.98 g. (0.01 mole) of maleic anhydride dissolved in 20 ml. of ether contained in a 125-ml. Erlenmeyer flask was added 0.94 g. (0.01 mole) of I. No heat was evolved and no precipitate formed on standing overnight at room temperature; however, when the solution was cooled in a refrigerator, the adduct crystallized as white needles, 1.90 g. (99%), m.p. 91-92°( petroleum ether, b.p. 30-40°).

O‐(2,4‐dinitrophenyl) oximes. Synthesis and cyclization to 5,7‐dinitrobenzofurans

“…We have recently reported (1) the application of the Fischer indole synthesis to the preparation of benzofurans. We wish to describe here the Fischer cyclization of 0-(2,4dinitrophenyl) oximes (In) to 5,7dinitrobenzofurans (IV).…”

“…Over sixty compounds of this type 413 were prepared but only those used for cyclization are described here. 2,4-Dinitrophenylhydrazones undergo the Fischer reaction only under severe conditions, using sulfuric acid in boiling acetic acid as catalyst (5). We used the same catalyst for the cyclization of compounds (UI) and obtained 5,7dinitrobenzofurans in 3045% yield.…”

SBA‐15‐Pr‐SO3H catalyzed one‐pot synthesis of indole derivatives via Fischer indole pathway

“…[31] The synthesized SBA-15 was then functionalized using sulfonic acid, [41] and the catalyst was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET). [31] The synthesized SBA-15 was then functionalized using sulfonic acid, [41] and the catalyst was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET).…”

“…SBA-15-Pr-SO 3 H was synthesized according to the procedure reported in the literature using template method. [31] The synthesized SBA-15 was then functionalized using sulfonic acid, [41] and the catalyst was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET). Also, the structure of catalyst particles was analyzed by SEM ( Figure 1).…”

Synthesis of Some New Substituted Photochromic N,N′‐Bis(spiro[1‐benzopyran‐2,2′‐indolyl])diazacrown Systems with Substituent Control over Ion Chelation

“…[13] Since it was envisaged that a relatively large quantity of the 5-nitrated indolenine would be required to complete the synthesis of 15c an alternative method was employed. We therefore prepared the 5-nitro-substituted indolenine [14][15][16] 6 (R 1 = NO 2 ) in good overall yield by the unambiguous but slightly longer Fisher indole synthesis, as shown in Scheme 1 (see Expt. Sect.…”