6- Substituted spiro decanes

For a route to spiro[4-5] decanes based on intramolecular keto-carbene insertion in substituted cyclohexenes, see M. Mongrain, J. LaFontaine, A. Belanger and P. Deslongchamps, Canad. j. Chem., 48, 3273 (1970) and P. M. McCurry, Tetrahedron Lett., 1845 (1971). An interesting synthesis of spiro systems by o, a annelation of enamines has been developed by D. J. Dunham and R. G. Lawton, J. Amer. Chem. Soc., 93, 2074 (1971). 

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