Synthesis of substituted benz[g]indole-6,9-diones and benzo[h]quinoline-7,10-diones by heterocyclization of 6-alkynyl-5-amino-1,4-naphthoquinones

Conjugated Ynones in Organic Synthesis

“…A crucial factor in these cases is the presence of at least one additional reactive moiety in the enaminones, in a position that makes it possible to interact with the enaminone motif. This is illustrated by the examples in Scheme 162 which show the reactivity of functionalized enaminones 354 under basic conditions with K 3 PO 4 (to pyrroles 356) 364 and t-BuOK (to pyridines 359), 365 acid catalysis (to benzoquinolinenaphtoquinones 361), 14 and metalinduced oxidations with cerium(IV) (to pyrroles 357 and 358), 357 copper(II) (to pyrroles 355), 359 and palladium(0) (to quinolones 360). 151 Finally, it should be mentioned that a change of the course of reaction has been observed when primary amines have been reacted with ynones with an aryl β-substituent containing a formyl group in the ortho position.…”

“…The oxidation of propargyl alcohols with chromium­(VI) reagents was initially performed with CrO 3 − and with pyridinium dichromate (PDC) for the synthesis of 25-hydroxy vitamin D2 . Recently ynone 3 , an intermediate in the synthesis of the natural product xanthofulvin (a promising lead for the spinal cord regeneration) has been achieved using PDC (Scheme ).…”

“…The reactions with ammonia and primary and secondary amines have been carried out under a variety of conditions. Some reactions have been performed at room temperature, ,,, but higher temperatures are more common, ,,− even as high as 120 °C , and 140 °C, and typically with 1.0–1.1 molar eq of the amine and no additional reagent(s), although the amine has also been used as solvent. ,,,, A variety of solvents have been applied, including alcohols ,, and nonprotic solvents like PhMe, , MeCN, DCM, THF, , DMSO, , 1,4-dioxane, , and DMF . The reaction time is usually short, but when anilines with one or several electron-withdrawing groups attached to the ring are used, even days have been required to obtain some product …”