Von Richter synthesis

Regitz reaction 263 Reissert reaction 409 Reissert synthesis (indole) 135 Remfiy-Hull synthesis (pyrimidine) 468 von Richter synthesis (cinnoline) 493 Ritter reaction 442... 

Raney nickel, 253 Reformatskii condensation, 30 Reformatskii reaction. 60,78-79 von Richter synthesis, 244 Ritter reaction, 94, 126-127 Rosenmund reduction, 50... 

The thermal cyclization of 2-alkynylbenzenediazonium salts represented by 2 to provide the 4-hydroxycinnoline derivatives 3 respectively is regarded as the von Richter cinnoline synthesis. " ... 

The first synthesis of cinnoline was reported by von Richter in 1883. The diazonium chloride 5 which was obtained from o-aminophenylpropiolic acid (4), was heated in water at 70°C to provide the 4-hydroxycinnoline-3-carboxylic acid (6). When this acid 6 was heated above its melting point, carbon dioxide was liberated and 4-hydroxycinnoline (7) was obtained. Distillation of 4-hydroxycinnoline (7) with zinc dust furnished a small amount of oil, which was assumed to be cinnoline (8). The preparation of 4-hydroxycinnoline (7) was repeated by Busch and Klett, although in lower yield when compared to the original report. Busch and Rast later converted the 4-hydroxycinnoline (7) successfully to cinnoline (8) via the 4-chlorocinnoline (9). ... 

The mechanism of the von Richter cinnoline synthesis has been discussed in several... 

The von Richter cinnoline process was further extended to solid-phase synthesis. The route began from benzylaminomethyl polystyrene and the required diverse o-haloaryl resins represented by 21 were prepared from substituted o-haloanilines. A Pd-mediated cross-coupling reaction with 21 and the alkynes provided the alkynylaryl derivatives represented by alkyne 22. The von Richter cyclization reaction with hydrobromic or hydrochloric acid in acetone/HaO and cleavage from the resin occurred in the same step to furnish the cinnoline derivatives 23 in 47-95% yield and 60-90% purity (no yield reported for each entry). 

See the Borsche Cinnoline Synthesis and the von Richter Cinnoline Synthesis for other preparations of cinnolines. 

REIMER TIEMANN Phenol formylation 314 REISSERT-GROSHEINTZ FISCHER Cyanoamme reaction 315 REPPE Acetylano reaction 3t6 von RICHTER Aromatic carboxylalion 317 von RICHTER - WIDMAN - STOERMER Cmndme synthesis 3t8 RILEY Selenaim dioxide oxidation 319 Rimmi 4... 

This reaction is related to the Widman-Stoermer Synthesis and von Richter Cinnoline... 

---