Alboinon, an oxadiazinone alkaloid from the ascidian Dendrodoa grossularia

Reactivity of 3-Cyanoacetylindole Derivatives: Synthesisof 3-Hydrazonopyrazolyl and 3-Thiadiazolyl Indole Derivatives

“…They show cytotoxicity toward murine tumor cell lines and have potent inhibition against several protein kinases [9,10]. Along with these, the substitution at the 3-position of the indole ring can take place by connecting an additional heterocyclic ring, such as imidazole (topsentins [11,12], nortopsentins [13]), dihydroimidazole (disc odermindole [14]), oxazole (martefragin [15], amazole [16]), oxadiazine (alboinon [17]), maleimide (didemidines [18]), and piperazine (dragmacidone [19]). Therefore, 3-substituted indoles still represent a significant synthetic challenge.…”

Application of (2Z)-3-dimethylamino-2-(1H-indole-3-carbonyl) acrylonitrile in the synthesis of novel 3-heteroarylindoles: condensed meridianine analogs

“…The formation of product 10 is assumed to take place via the addition of the exocyclic amino group in 2-aminobenzimidazole to the activated double bond in the enaminonitrile 2 to give the acyclic non-isolable intermediate 9 which undergo intramolecular cyclization and subsequent aromatization via the loss of dimethylamine under the reaction conditions to afford the final product 10 as depicted in Scheme 3. The structure of the pyrimido[1,2-a]benzimidazole 10 was further confirmed by its alternate synthesis via the reaction of 3-cyanoacetyl indole (1) with N`-(1H-benzimidazol-2-yl)-N,Ndimethylformamidine (11) 37 which afforded product identical in all respects (mp, mixed mp, TLC, IR, and mass spectra) with that obtained from the reaction of the enaminonitrile 2 with 2-aminobenzimidazole as shown in Scheme 3.…”

“…[1][2][3][4] Along with these, 3-substituted indoles represented promising structural class of marine alkaloids based upon their high degree of biological activity. The substitution at 3-position of the indole ring connecting an extra heterocyclic ring: imidazole (topsentins 4,5 and nortopsentins 6 ); dihydroimidazole (discodermindole 7 ); oxazole (martefrgin 8 , amazol 9 ); oxadiazine (alboinon 10 ); maliemide (didemidines 11 ); piperazine (dragmacidon 3 ); and pyrimidine (meridianins), recently isolated from the tunicate Splidium meridiaum. 12,13 Furthermore, indole containing compounds has been reported to possess a wide variety of biological properties viz., anti-inflammatory,…”

Engineering of indole-based tethered biheterocyclic alkaloid meridianin into β-carboline-derived tetracyclic polyheterocycles via amino functionalization/6-endo cationic π-cyclization

“…The presence of a heterocyclic ring at the position 3 of the indole represents an important class of marine alkaloids, such as oxazole (martefragin [17], amazol [18]), imidazole (topsentins [19–20] and nortopsentins [21–23]), dihydroimidazole (discodermindole [24]), oxadiazine (alboinon [25]), piperazine (dragmacidon [26]), maleimide (didemidines [25]), and pyrimidine (meridianins) [27–29]. Among these, meridianins (Fig.…”