CONVENIENT ROUTE TO 2H-FURO[3,2-c]QUINOLIN-4-ONE FRAMEWORK USING Mn(III)-BASED OXIDATIVE RADICAL CYCLIZATION

Mn(III)-based reaction of alkenes with quinolinones. Formation of peroxyquinolinones and quinoline-related derivatives

“…2.3. Mn(III)-mediated oxidation of alkenes in the presence of 4-hydroxyquinolin-2(1H)-ones and other related compounds 14 4-Hydroxyquinolin-2(1H)-ones 2 as a reagent are very good candidates not only as a radical source in the Mn(III)-mediated oxidation, 3 but also as a starting material for the synthesis of quinolinone alkaloids such as atanine, araliopsine, and isoplatydesmine. 10c The 1,3-dicarbonyl compounds, such as 2,4pentanedione, malonic acid, malonate esters, acetic anhydride, malonamides, and 3-oxobutanoates, undergo oxidative cyclization with alkene using Mn(OAc) 3 $2H 2 O at elevated temperature to produce dihydrofurans, 10 spirolactones, 11a,b g-lactones, 11c,eeg lactams, 4c,11hej and dihydroquinolinones.…”

“…Gratifyingly, the 4-hydroxyquinolinone analogue, 14 such as 4hydroxy-5,6,7,8-tetrahydroquinolin-2(1H)-one ( 11), 1-benzyl-4hydroxy-5,6-dihydropyridin-2(1H)-one ( 13), 4a 4-hydroxy-2Hchromen-2-one ( 15), 10h and 4-hydroxy-6-methyl-2H-pyran-2-one (17) also underwent the oxidative cyclization with alkenes 1 to afford the corresponding 2,3-dihydrofuro[3,2-c]pyridin-4-ones 12, 14 and furo[3,2-c]pyran-4-ones 16aec, 18 in moderate to high yields (Table 4, entries 1e6). The cyclization only took place at the enolic ketocarbonyl group, and no products cyclized at the amide and ester carbonyl groups were isolated.…”

“…2.4. Mn(III)-mediated oxidation of a mixture of alkenes 2 and 3-substituted quinolinones 6 14 We were next interested in the Mn(III)-mediated oxidation of quinolinones having a substituent at the 3-position since the deprotonation could not occur at the intermediate cation I stage in Scheme 5. The oxidation of a mixture of alkene 1 (Ar¼Ph) and 3substituted quinolinone 6 (R¼Me) with Mn(OAc) 3 $2H 2 O was then carried out at the reflux temperature.…”

“…13 A similar reaction using a stoichiometric amount of Mn(III) at elevated temperature formed furo [3,2-c]quinolin-4(2H)-ones and 3vinylquinoline-2,4-diones. 14 In this paper, we describe the results of the oxidation of a mixture of 1,1-disubstituted alkenes and 4hydroxyquinolinones, and the synthetic application of the dihydrofuranation using the quinolinones and related 1,3-dicarbonyl compounds together with the full experimental results of these reactions.…”