McKillop rearrangements

Treatment of [ C]methyl aryl ketones with thaUium(lll) nitrate in acidic methanol (McKillop rearrangement) or with ammonium polysulfide or sulfur and morpholine at elevated temperatures (Willgerodt-Kindler reaction) provides labeled arylacetic acid derivatives. In the first case the aryl group migrates from the carbonyl position into the former methyl position, so that the label is shifted by one position. For example (Figure 6.12), in the synthesis of [6- / C]porphobilinogen the pyrrole 22 was acetylated with... 

Finally, recent work has disproved the originally proposed structure 226303 of the product from addition of DMAD to benfothiazole. McKillop and Sayer304 have shown that a first-formed adduct 227 can give a fused thiazole 228 by addition of a second DMAD molecule, or rearrange to the benzothiazine 229 in the presence of water. The structure of 229 was established by X-ray crystallography.305... 

Reaction with benzothiazole. McKillop and Sayer have clarified the reaction of benzothiazole (1) with DMAD for which conflicting results had been reported. Under strictly anhydrous conditions the 1 2 adduct (2) is formed, albeit in low yield. If water is present, (3) is formed in virtually quantitative yield. The chemists suggest that an initial dipolar adduct (a) is formed, which can react with DMAD to form (2) or with water to form (b), which rearranges to (3). 

E. C. Taylor, A. McKillop, and coworkers. Thallium in organic synthesis 49. Oxidative rearrangement of chalcone dimethylketals to methyl-2,3-diaryl-3-methoxypropanoates with thallium(m) trinitrate in trimethylorthoformate. J. Org. Chem., 1977, 42, 4167 50. A convenient synthesis of thallium(i) cyanide, a useful reagent in organic synthesis (for conversion of aroyl chlorides to aromatic a-ketonitriles). J. Org. Chem., 1978, 43, 2280 51. Oxidation of enolizable ketones to a-nitratoketones by thallium(in) nitrate in acetonitrile. 

First example Ogg and Bergstrom (1931) published a series of papers designed to demonstrate possible analogies between heterocyclic systems and their acyclic and alicyclic counterparts. Quinoxaline, for example, was described as an ammono glyoxal and 2,3-diphenylquinoxaline 1 was considered to be the heterocyclic equivalent of benzyl. In an attempt to justify this hypothesis, the authors carried out the reaction of 2,3-diphenylquinoxaline 1 with potassium amide in liquid ammonia, anticipating a reaction similar to the benzyl —> benzilic rearrangement, which would lead to the formation of 2,2-diphenyl-3-aminoquinoxaline 2 (Scheme 6.1). The reaction did, in fact, lead to a new product-2-phenylbenzimidazole 3 in an approximately 30 % yield and the recovery of about 60 % of unchanged 2,3-diphenylquinoxaline 1 (Taylor and McKillop 1965). 

McKillop A, Hunt JD, Kienzle F, Bigham E, Taylor EC. Thallium in organic synthesis. 32. Oxidative rearrangement of olefins using thallium(III) nitrate (TTN). J. Am. Chem. Soc. 1973 95 3635-3640. 

Figure 6.12 McKillop and Willgerodt-Kindler rearrangements of [ Clacetyl aryls and heteroaryls...

---