Stetter thiazolium salt method

For reviews, see Sielter Kuhlmann Org. React. 1991, 40, 407-496 Stetier Angew. Chem. Int. Ed. Engl. 1976, IS, 639-647 [Angew. Chem. 88, 695-704). For a similar method involving thiazolium salts, sec Stetter, Kuhlmann Chem, Her. 1976, 109, 2890 Stetter Skobel Chem. Ber. 1987, 120, 643 Stetter Kuhlmann Haese Org. Svruh. 65. 

Any of the d1 reagents suggested in chapter 25 would do but they preferred a catalytic method using the thiazolium salts 25 devised by Stetter.4 These are also aromatic heterocyclic compounds... 

---