Buchner Method of Ring Enlargement

E. Buchner, Ber. 29, 106 (1896); E. Buchner, K. Schottenhammer, Ber. 53, 865 (1920).

Diazoacetic acid ester reacts with benzene and homologs to give the corresponding esters of noncaradienic acid, transformed at high temperatures to derivatives of cycloheptatriene and phenylacetic acid:

W. von F. Doering, L. H. Knox, J. Am. Chem. Soc. 79, 352 (1957); W. Kirmse, Carbene Chemistry (Academic Press, New York, 2nd ed., 1971); A. F. Noels et al., J. Org. Chem. 46, 873 (1981). Cf. Pfau-Plattner Azulene Synthesis.