Lanthanum(III) nitrate hexahydrate or p-toluenesulfonic acid catalyzed one-pot synthesis of 4(3H)-quinazolinones under solvent-free conditions

Iodine Catalyzed One‐pot Synthesis of 3,4‐Dihydroquinazolin‐4‐ones from Anthranilic Acids, Ortho Esters and Amines under Solvent‐free Conditions

“…In conclusion, iodine was found to be an efficient catalyst for the one-pot reaction of anthranilic acids with Scheme 1 Possible mechanism of iodine catalyzed synthesis of 3,4-dihydroquinazolin-4-ones (4) orthoesters and amines under solvent-free conditions to afford 3,4-dihydroquinazolin-4-ones (4) in excellent yields. The direct use of commercially available catalyst, mild and solvent-free reaction conditions, short reaction time, easy workup and excellent yields are the advantages of the present protocol.…”

“…2 However, some of these methods are associated with drawbacks such as multi-step procedures, costly reagents, harsh reaction conditions and unsatisfactory yields. Recently, a concise and practical one-pot synthesis of quinazolones from anthranilic acid, ortho esters and amines promoted by Yb(OTf) 3 , 3 La(NO 3 ) 3 •6H 2 O or p-toluenesulfonic acid, 4 SiO 2 -FeCl 3 , 5 Ye(III)-resin 6 and NaHSO 4 •SiO 2 or amberlyst-15 7 has been reported. In recent years, the use of molecular iodine as a cheap and easily available catalyst has received considerable attention for various organic transformations 8 such as synthesis of decahydroquinolinones, 9 dihydroperoxidation of ketones, 10 synthesis of quinolines, 11 synthesis of Cbz-protected β-amino ketones, 12 imino Diels-Alder reaction 13 and cross-aldol condenation.…”

Synthesis of 2-(2-Aminophenyl)-4-arylquinazoline Derivatives by Reaction of 2-Aminoarylbenzimidamides with Isatoic Anhydride

“…Most of the known syn-0932-0776 / 09 / 0800-0945 $ 06.00 c 2009 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com theses of quinazoline derivatives, such as those using various catalysts such as Yb(OTf) 3 [15], Nafion-H [16], Bi(TFA) 3 -FeCl 3 [17], silica gel/FeCl 3 [18], La(NO 3 ) 3 ·6H 2 O [19], and KAl(SO 4 ) 2 ·12H 2 O [20] require either reflux for several hours in a large volume of solvent, or the use of an expensive catalyst. Continuing our work on the synthesis of 2,4-disubstituted quinazoline derivatives, in this report we describe the reaction of 2-aminobenzimidamides 3a -j with isatoic anhydride (4) as a simple approach for 2,4-disubstituted quinazolines.…”

A mild and efficient synthesis of chiral tetrahydroquinolino pyranose derivatives catalyzed by lanthanum(iii) nitrate hexahydrate

“…On the other hand, organic reactions using a water-tolerant catalyst also received much attention in recent years, as they can be handled conveniently and removed from the reaction mixture, making the experimental procedure simple and ecofriendly. Recently, we explored La(NO 3 ) 3 ·6H 2 O as a mild and efficient catalyst for the chemoselective tetrahydropyranylation of primary alcohols [19], chemoselective deprotection of acetonides [21], synthesis of quinazolinones [22], for acetylation of alcohols, phenols, and amines [20], synthesis of α-amino nitriles [23], N-benzyloxycarbonylation [24], N-tertbutoxycarbonylation of amines [25], thioacetylation of aldehydes [26], chemoselective protection of alcohols as their pivaloyl esters [27], and for efficient cleavage of cyclic and acyclic ethers [28]. In the above transformations, it has been observed that the substrates containing acid labile functional groups such as acetonides, TBDMS ethers, some isopropylidene-protected diols, and N-tertBoc-protected amines were intact in the presence of La(NO 3 ) 3 ·6H 2 O.…”