Spirobenzannulated compounds

A novel hypervalent iodine-induced direct intramolecular cyclization of a-(aryl)alkyl-jS-dicarbonyl compounds 33 has been recently reported (Scheme 15) [30]. Both meta- and para-substituted phenol ether derivatives containing acyclic or cyclic 1,3-dicarbonyl moieties at the side chain undergo this reaction in a facile manner affording spirobenzannulated compounds 34 that are of biological importance. 

The hypervalent iodine-induced direct intramolecular cyclization of a-(aryl)alkyl-p-dicarbonyl derivatives 305 affords biologically important spirobenzannulated compounds 306 (Scheme 3.125) [366]. 

Arisawa, M., Ramesh, N.G., Nakajima, M., Tohma, H., and Kita, Y, Hypervalent iodine(lll)-induced intramolecular cychzation of a-(aryl)alkyl-P-dicarbonyl compounds a convenient synthesis of benzarmulated and spirobenzannulated compounds, /. Org. Chem., 66, 59, 2001. Eberson, L., Reaction between organic and metal ion species, in Electron Transfer Reactions in Organic Chemistry, Reactivity and Structure, Vol. 25, Hafner, K., Lehn, J.-M., Rees, C.W., von Rague-Schleyer, R, Trost, B.M., and Zahradnik, R, Eds., Springer-Verlag, Berhn, 1987, chap. 7. Bockman, T.M., ShuMa, D., and Kochi, J.K., Photoinduced electron transfer from enol silyl ethers to quinone. Part 1. Pronounced effects of solvent polarity and added salt on the formation of a-enones, J. Chem. Soc., Perkin Trans. 2, 1623, 1996. 

A hypervalent iodine-induced intramolecular cyclization of the a-(aryl)alkyl-P-dicarbonyl compound 482 furnishes the spirobenzannulated chroman 483 in good yield (Equation 197) <2001JOC59>. 

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