... References and notes. 1; (a) M. Hesse; Ring Enlargement in Organic Chemistry. VCH, Weinheim (1991). (b) L. Yet; Tetrahedron, 55 (1999), pp. 9349–9403. ... 4; (a) RW Thies, H.-HJ Shih; J. Org. Chem., 42 (1977), pp. 280–281. ... J. Org. Chem., 68 (2003), pp. 433–441. ...