Pfau-Plattner Azulene Synthesis

A. St. Pfau, P. A. Plattner, Helv. Chim. Acta 22, 202 (1939).

Formation of azulenes by ring enlargement of indanes on addition of diazoacetic ester, hydrolysis, dehydrogenation and decarboxylation of the resulting acid:

P. A. Plattner et al., ibid. 23, 907 (1940); 24, 483 (1941); 25, 590 (1942); B. Eistert, Newer Methods of Preparative Organic Chemistry (Interscience, New York, 1948) p 555; D. H. Reid, Chem. Soc. Spec. Publ. 12, 69 (1958); K. Hafner, Angew. Chem. 70, 419 (1958). Cf. Buchner Method of Ring Enlargement.