New formal (3+3) cycloaddition of enaminones for forming tetracyclic indolo[2,3-b]quinolines under microwave irradiation

Microwave-Assisted Synthesis of Bioactive Six-Membered Heterocycles and Their Fused Analogues

“…For example, chloroquine (46) has been used for its antimalarial activity for more than 60 years; [56][57][58] bedaquiline (47), an inhibitor of the mycobacterial ATP synthase, has been approved to treat multi-drug resistant tuberculosis, [59] and cabozantinib (48), a multitargeted receptor tyrosine kinase inhibitor, showed effective anticancer activity and has been marketed for the treatment of medullary thyroid cancer ( Figure 4) [60]. Therefore, in the last decade, several new synthetic routes to quinoline derivatives under MW-irradiation have been reported [61][62][63][64][65][66]. Kulkarni et al [61] described a solid acid-catalyzed synthesis of substituted quinolines via a MW-assisted three-component domino reaction between anilines, aldehydes and terminal aryl alkynes.…”

“…The combination of solid acid catalysis, multicomponent domino reaction approach and microwave irradiation provided the quinolones 52 in excellent selectivities and short reaction times (Scheme 10). Therefore, in the last decade, several new synthetic routes to quinoline derivatives under MW-irradiation have been reported [61][62][63][64][65][66]. Kulkarni et al [61] described a solid acid-catalyzed synthesis of substituted quinolines via a MW-assisted three-component domino reaction between anilines, aldehydes and terminal aryl alkynes.…”

“…Very recently, Li et al [63] have developed a new synthesis of tetracyclic indolo [2,3-b]quinolone derivatives 61 via domino heterocyclization of 3-aroylidene-2-oxindoles 59 with enaminones 60 in a sealed vessel under microwave irradiation. The reaction cascades consisted of an initial Michael addition, tautomerism, intramolecular cyclization, and dehydration leading to aromatization (Scheme 12).…”

Syntheses of Enaminone-Based Heterocyclic Compounds and Study their Biological Activity

“…Fur thermore, the enaminone 2 was cyclocondensed with 2-amino thiophenol in refluxing AcOH to afford 3-(benzo[b] [1,4]thiazepin-2-yl)-2H-chromen-2-one (10) via the intermediate 9, which subsequently cyclized through elimination of molecule of water as shown in scheme 3. For this reaction there are three possible isomer products 10, 11 and 13.…”

“…Enaminones are versatile precursors that have been utilized extensively as building blocks in organic synthesis [3][4][5][6][7][8][9][10][11][12] , such compounds are synthetic precursors for the synthesis of a broad diverse of naturally occurring alkaloids 13 and nitrogen-containing heterocycles 14 .…”