A facile and efficient carbodiimide-mediated synthesis of dihydroquinazolines via a tandem nucleophilic addition-intramolecular hetero conjugate addition annulation strategy

Synthesis of pyrido and pyrazinodithienodipyrimidine-4,8(3H,9H)-dione derivatives by the aza-Wittig methodology

“…These selectivity results can probably be explained by the large difference in cyclization rates due the steric hindrance around the Ph and isopropyl or butyl groups. 21 Mass and spectroscopic data are in good agreement with the proposed structures. The FABmass spectra show the expected molecular ion peaks and the fragmentation pattern is in accord with the proposed structures.…”

Lewis Acid‐Catalyzed or Base‐Promoted Regioselective Cycloisomerization of N‐Imidoyl‐o‐alkynylanilines for Synthesis of N‐Imidoyl‐(1 H)‐indoles and 4‐Alkylidene‐3,4‐dihydroquinazolines

“…(4)) 9d. 13 The reaction is highly regioselective, but unfortunately the scope of the substituents seemed to be rather limited (R 1 =Ph; R 2 =aryl group only).…”

Stereoselective synthesis of 4H-3,1-benzothiazines via tandem nucleophilic addition/epoxy ring-opening cyclization reactions of 2-(3-phenyloxiranyl)phenyl isothiocyanates

“…From our ongoing interest in the synthesis of nitrogen-containing heterocycles through a tandem methodology of functionalized azacumulenes (11)(12)(13)(14), we previously demonstrated the tandem nucleophilic addition/intramolecular hetero-Michael addition cyclization (12;Equation (1)) and iodocyclization of carbodiimides to give quinazolines and N -ring fused benzothiadiazine-S,S-dioxides (13; Equation (2)). Quite recently, we also disclosed a conventional synthesis of 4-aryl-quinoline-2-thiones via the tandem Friedel-Crafts alkenylation/cyclization reaction of o-alkynylphenyl isothiocyanates (14; Equation (3)).…”