Facile Synthesis of Novel Indeno[1,2‐b]indol‐10‐one Derivatives by the Oxidation with DDQ

Synthesis, crystal structure and effect of indeno[1,2-b]indole derivatives on prostate cancer in vitro. Potential effect against MMP-9

“…Among the existing procedures for the preparation of indenoindoles, the Fischer indolization starting with an indanone, via the respective phenylhydrazones, serves as the most common method [24,25]. Recently, two new syntheses by transformation and reduction of 2-nitrobenzylidenephtalide, generated either by intramolecular cyclization of 2-(2-nitrophenylethyl)benzoic acid [26], or by reaction of a phthalidyl-phosphonium bromide with 2-nitrobenzaldehyde [27] and cyclization of the resulting amino compounds, M A N U S C R I P T…”

Friedel-Crafts 3-(2-Bromobenzoylation) of Indoles and Intramolecular Direct Arylation: An Efficient Route to Indenoindolones

“…2 Indenoindolones are also used as intermediates in the synthesis of potential therapeutic agents. 1c,e,3 Current approaches to the synthesis of indeno [1,2-b]indol-10(5H)-ones include: (1) the preparation of benzylidene phthalide in four steps and its rearrangement to indane-1,3-dione mediated by strong base followed by reductive cyclization, 1a,b,e (2) lithium diisopropylamide induced anionic N→C carbamoyl migration of 2-aryl-1-(carbamoyl)indoles, Boc derivatization, and lithium 2,2,6,6,-tetramethylpiperidide induced cyclization, 4 (3) cyclocarbonylation of NH-protected 3-iodo-2-phenylindoles, 5 (4) Fischer indolization reaction of arylhydrazone derivatives of indan-1-one to afford indenoindole and subsequent benzylic oxidation, 6 and (5) reaction of cyclic enaminone with ninhydrin, de-dihydroxylation, and oxi-dation. 1d Recently, a method for the reductive cyclization of 3-hydroxy-2-(2-nitrophenyl)-1H-inden-1-ones was reported.…”

“…The highest yield of product for the intramolecular arylation of 3-(2-bromobenzoyl)-1-methyl-1H-indole (3a) was obtained utilizing Pd(dppf) 2 Cl 2 •CH 2 Cl 2 as catalyst, potassium carbonate as base, and N,N-dimethylformamide as solvent (entry 5). Variation in equivalence of potassium carbonate revealed that two equivalents were sufficient (entries [4][5][6]. For the intramolecular arylation of 3-(2-bromobenzoyl)-1H-indole (3f), the reaction with palladium(II) acetate, triphenylphosphine, cesium acetate, in N,N-dimethylacetamide solvent was found to be best (entry 9).…”

Synthesis and Crystal Structure of (4bRS,9bRS)-5-(2,4-dimethoxyphenyl)-4b,9b-7,7-dimethyldihydroxy-4b,5,6,7,8,9b-hexahydroindeno[1,2-b] indole-9,10-dione

“…Among the existing procedures for the preparation of indenoindoles, the Fischer indolisation starting with an indanone, via the respective phenylhydrazones, serves as the most common method. 8,9 Recently, two new syntheses by transformation and reduction of 2-nitrobenylidenephtalide, generated either by intramolecular cyclisation of 2-(2-nitrophenylethyl) benzoic acid 10 or by reaction of a phthalidyl-phosphonium bromide with 2-nitrobenzaldehyde, 5 and cyclisation of the resulting amino compounds, have been published. The formation of vic-dihydroxy-indenoindolones by the reaction of ninhydrine 1 with aliphatic, and aromatic amines, or alicyclic, and cyclic enaminones has been reported elsewhere.…”