Vilsmeier s reagent

The Meth-Cohn quinoline synthesis involves the conversion of acylanilides 1 into 2-chloro-3-substituted quinolines 2 by the action of Vilsmeier s reagent in warmed phosphorus oxychloride (POCI3) as solvent. ... 

Condensation of 8-(substituted amino)-l,5-dihydro-5-deazaflavins with 6-chloro-5-formyluracil gave bis-dihydro-5-deazaflavins and 8-(5-formyluracil-6-yl)amino-l,5-dihydro-5-deazaflavins. The dehydrogenation of the former with DEAD or the dehydrative cyclization of the latter with Vilsmeier s reagent gave the pentacyclic derivatives (172) <84CC872,88JCS(P1)1809>. 

Substitution of chlorine for hydroxyl at C-6 of morphine was effected098 with dimethylchloroformiminium chloride (Vilsmeier s reagent) in DMF. The resultant a-chloromorphide (90, R = H X = Cl), together with the 6a-bromo- and 6a-iodo- derivatives, was described earlier.075 199 The 6-halide configuration was determined as 6-axial by H nmr.098 The kinetics of SN2 ... 

The reaction of acetanilides (72) with Vilsmeier s reagent in POCl3 is an efficient route to 2-chloroquinoline-3-aldehydes (73) by diformylation of the side chain. In those cases where cylization does not occur efficiently (e.g., R = Cl or Br) the hydrolyzed intermediate (74) may be separately cyclized with polyphosphoric acid (PPA) to give the quinolones (75).31-59... 

In contrast to other (benzo)pyridazines, 1//-benzo[fi e]cinnolines show a marked susceptibility to electrophilic attack due to the pyrrole-like N-1 and, for example, 6-methoxy derivatives undergo formylation at C-7 and C-9 with Vilsmeier s reagent <81ZOR2444> and condenses with aldehydes at C-9 <82ZOR415>. 

Scheme 9.31. Synthesis of imidazoles using Vilsmeier s reagent.

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