An efficient method for the rapid construction of carbo- and heterocycles has been developed using radical relay cyclizations initiated by alkoxy radicals. Linear substrates were cyclized to form a wide range of cyclopentane, pyrrolidine, tetrahydropyran, and tetrahydrofuran derivatives in excellent yields. This methodology was utilized as a key step in the synthesis of the tetrahydrofuran fragment in (-)-amphidinolide K.

The highly efficient and diastereoselective synthesis of E dienes has been accomplished through radical cyclization of bromoallyl hydrazones. This methodology has been further extended to generate these products through a one-pot condensation/radical cyclization/cycloreversion cascade from simple aldehyde starting materials in high yields (>75%) and high diastereoselectivities (>95:5). Mechanistic investigations suggest that the cascade reaction proceeds through a cyclic diazene intermediate prior to the cycloreversion.

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The highly efficient and diastereoselective synthesis of E dienes has been accomplished through radical cyclization of bromoallyl hydrazones. This methodology has been further extended to generate these products through a one-pot condensation/radical cyclization/cycloreversion cascade from simple aldehyde starting materials in high yields (> 75 %) and high diastereoselectivities (> 95:5). Mechanistic investigations suggest that the cascade reaction proceeds through a cyclic diazene intermediate prior to the cycloreversion.Scheme 4. One-pot hydrazone formation followed by one-electron/ pericyclic cascade for the synthesis of dienes 4 d, 4 e, and 4 f. Angewandte Chemie 6343