4) De Vries, L. J. Am. Chem. SOC. 1978,100, 926. (5) Kosower, E. M.; Waits, H. P.; Teuerstein, A.; Butler, L. C. J. Org. Chem. 1978,43,800. (6) A special effect on polysubstituted radical stabilization has been first suggested by theoretical argument by (a) Dewar, M. J. S. J. Am. Chem. SOC. 1952,74,3353 and then observed experimentally and termed 'push-pull stabilization by (b) Balaban, A. T. Rev. Roum. Chim. 1971, 16,725 and "meroetabilization" by (c) Baldock, R. W.; Hudson, P.; Katritzky, A. R.; Soti, F. J. Chem. SOC., Perkin Trans. 1 1374,1422. See also: (d) Aurich, H. G.; Deuschle, E.; Weiss, W.

Dedicated to the double anniversary: 100 years Wurster's salts and SO years Paneth's radical reactions with metal mirrorsThe 100 years old Wurster's salts have long been recognized as compounds with radical cations. Their unusual stabilization derives partly from capto-dative (cd) substitution. This principle is now discussed as one factor of radical stabilization and it is applied to simple methine derivatives. cd-Substitution has synthetically useful applications: cd-substituents on a carbon atom allow its selective dehydrodimerization. Olefins with geminal and thus cross-conjugated cd-substituents are "radicophilic" and permit twofold carbon radical addition. cd-Substituted olefins are useful antioxidants, polymerization inhibitors and are promising agents in the control of biological radical reactions. Generally, many reactions of cd-substituted molecules appear to involve radicals.Angew. Chem. Int. Ed. Engl. 18, 917-932 (1979) 0 Verlag

Dedicated to Professor Jean-Marie Surzur on the occasion of his 50th birthdayMany N-chloroalkylamines with double bond(s) dissociate homolytically to give chlorine atoms and aminyl radicals which undergo intramolecular cyclization reactions. Here, the nature of the aminyl radicals (neutral, protonated, or complexed to metal salts) appears to be important. The reactivity varies strongly from one species to another, and their selectivities can be different towards addition, substitution, abstraction, or dimerization reactions. A good synthetic tool appears to be the "complexed radical", which is generated under mild conditions. A variety of 0-functionalized, substituted, fused, or bridged azaheterocycles with alkaloid part structures thus become easily accessible in high yields, in a regio-and, possibly, stereoselective manner. Many examples are discussed illustrating the synthetic possibilities, limitations, and mechanistic features of this cyclization process.

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