Radical reactions cascades

An extremely interesting example of cascade radical reactions has been reported recently <93TL5653>. The initial radical generation from the 3-bromothiophene (565) is brought about by tributyltin hydride. This is then followed by cyclization, fragmentation, recyclization by the 5-exotrig mode and a final fragmentation. After all this, the product (566) is obtained in 74% yield (Scheme 120). 

Benati L, Calestani G, Leardini R, Minozzi M, Naimi D, Spagnolo P, Strazzari S, Zanardi G (2003) Cascade radical reactions via a-(arylsulfanyl)imidoyl radicals competitive [4-1-2] and [4+1] radical annulations of alkynyl isothiocyanates with aryl radicals. J Org Chem 68 3454-3464... 

Pattenden, G. and Schulz, D.J. (1993) Cascade Radical Reactions in Synthesis. A New Radical Mediated Double Ring Expansion-Cyclization Process with Oxime Ethers, Tetrahedron Lett. 34, 6787-6790. 

Pig. 9 Different radical cyclizations investigated in ref. 95 1 cyclization of hexenyl radicals, II cyclization of acyl-substituted hexenyl radicals and III cascade radical reactions. (Reproduced with permission from /. Org. Chem., 2007, 72, 348. Copyright 2007 American Chemical Society). 

Tandem and Cascade Radical Reactions. An efficient carbonylation procedure can be achieved by a three-component... 

The radical chemistry of organotins is overwhelmed by the tin hydride chemistry. In the past decades, the knowledge of kinetic parameters authorized the expeditious construction of complex molecules by using cascade radical reaction based on BujSn" methodology. Moreover, these strategies also offered an excellent dia-stereocontrol, especially for the construction of polycyclic skeletons. These synthetic applications of BujSnH, which will not be covered in this chapter, were reviewed in recent years [279]. In addition to the tin hydride chemistry, there are several applications of organotins in radical syntheses involving mainly allylstan-... 

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