Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• -pot synthesis of substituted dihydroquinazolines 35 from a variety of o-aminobenzylamines with appropriate aldehydes and alkylnitrates. The initial condensation of substituted o-aminobenzylamines with aldehydes afforded the substituted tetrahydroquinazoline 34, which was subsequently treated with a

• heterocyclic precursors [63]. A variety of substituents were well tolerated on both quinazoline and on the appended aromatic ring to generate the desired compounds 48 in moderate to excellent yield. The reaction conditions involved refluxing of 2-aryl-1,2,3,4-tetrahydroquinazoline 47 in chloroform for twelve

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• overview and selection of examples out of numerous compounds incorporating the aminal system as the essential structural feature. Especially the aminal-bearing tetrahydroquinazoline system is of great interest as a structure derived from the quinazolinone and quinazoline cores. These represent privileged

• ] (Scheme 2). Furthermore, copper-catalysed reactions or oxidation with sodium hypochlorite were also described to yield the aromatic quinazoline core [26][29][30] (Scheme 2). Besides all the oxidation reactions described, also reductive conditions applying NaBH4 onto the tetrahydroquinazoline-based aminal

• amides 5a–d using the corresponding free amines or their salts. Cyclization towards dihydroquinazolinones 6a–f and 7a–c was performed using benzaldehyde derivatives under acidic conditions with moderate to excellent yields. The tetrahydroquinazoline target compounds 8a–f and 9a–c were finally obtained by

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation

• Xiaofeng Zhang,
• Kenny Pham,
• Shuai Liu,
• Marc Legris,
• Alex Muthengi,
• Jerry P. Jasinski and
• Wei Zhang

Beilstein J. Org. Chem. 2016, 12, 2204–2210, doi:10.3762/bjoc.12.211

• formaldehyde through [5 + 1] annulation to afford a novel polycyclic scaffold bearing tetrahydroquinazoline, pyrrolidine, pyrrolidinedione, and N-substituted maleimide in stereoselective fashion. Keywords: [5 + 1] annulation; [3 + 2] cycloaddition; one-pot reactions; stereoselective synthesis

• ; tetrahydroquinazoline; Introduction The synthesis of new molecules with potential biological activity through pot, atom and step-economic (PASE) reactions is an attractive green organic technique [1][2][3][4][5]. By the combination of multicomponent reactions (MCR) [6][7][8][9][10][11] with stepwise one-pot reactions

• new sequence initiated with a three-component [3 + 2] cycloaddition for preparing polycyclic scaffold 1 bearing tetrahydroquinazoline, pyrrolidine, pyrrolidinedione, and N-substituted maleimide rings. Those heterocyclic fragments could be found in bioactive compounds such as bromodomain, thrombin

Selective copper(II) acetate and potassium iodide catalyzed oxidation of aminals to dihydroquinazoline and quinazolinone alkaloids

• Matthew T. Richers,
• Chenfei Zhao and
• Daniel Seidel

Beilstein J. Org. Chem. 2013, 9, 1194–1201, doi:10.3762/bjoc.9.135

• strong bases. Han et al. have recently shown the ability of copper salts, in conjunction with oxygen, to catalyze oxidations of 2-substituted tetrahydroquinazoline aminals to quinazolines [35] (Figure 2). In addition, Reddy and co-workers have developed a catalytic system in which 2,3-substituted

• tetrahydroquinazoline aminals are converted to quinazolinones using tert-butylhydroperoxide (TBHP) and catalytic potassium iodide [36][37]. While these examples deal with the oxidation of bicyclic aminals, we were interested in developing methods to create dihydroquinazoline and quinazolinone alkaloids from ring-fused