In nitrogen heterocyclic systems

Claisen Rearrangements in Nitrogen Heterocyclic Systems B. S. Thyagarajan, Adv. Heterocycl. Chem., 1967, 8, 143-163. 

Chrom-3-ene chemistry, advances in, 18, 159 Claisen rearrangements, in nitrogen heterocyclic systems, 8, 143... 

Claisen rearrangements in heteroaromatic systems, 42, 203 in nitrogen heterocyclic systems, 8, 143 Complex metal hydrides, reduction of nitrogen heterocycles with, 6, 45 39, 1 Concept of aromaticity in heterocyclic chemistry, 56, 303 Condensed heterocyclo[n,m- , b, or cjquinazolines, 52, 1 Condensed 4-thiazolidinones, 49, 1... 

The synthesis of the allyl ethers in nitrogen heterocyclic systems presents an element of complication in that the allylation could occur on the oxygen atom or the basic nitrogen atom. This is a feature of alkylation of ambident anions.3 However, this applies only when the allylation is effected by reacting the oxo or hydroxy derivative of the compound with an allyl halide in the presence of a base.3 The alternative method is to react the appropriate halo derivative with sodium allyloxide in allyl alcohol. The latter approach provides not only better yields of the allyl ethers but also certainty of the constitution of the ethers obtained. A diagnostic tool in deciding between the 1-allyl derivative and the O-allyl compound that has commonly been employed is the infrared absorption of the amide carbonyl in the case of the former which is clearly absent in the latter. 

The Claiaen rearrangement in nitrogen heterocyclic systems has been carried out in many different solvents. The ease of allylic migration appears to vary considerably among the different systems. The solvent media commonly employed are diethylaniline, 1-methyl-naphthalene, and AjA-diethyl-m-toluidine (b.p., 231°). In other instances, where the allyl ethers are liquids, the rearrangement has also been effected without any solvent. Under these conditions, the results are not always the same as those observed with a solvent. 

Thyagarajan, B. S., Aromatic Quinolizines, 5,291 Clalsen Rearrangements in Nitrogen Heterocyclic Systems, 8,143. 

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