Regio- and diastereoselective synthesis of functionalized hydroxyhexahydrocyclopenta[b]furancarboxylates by oxidative radical cyclization of cyclic β-keto esters with alkenes

One-Electron Oxidation of Geranyl Acetone Derivatives Using Ceric(IV) Ammonium Nitrate and Manganese(III) Acetate: Carbon–Carbon Bond Formation

Oxidation of geranyl acetone derivatives with ceric ammonium nitrate (CAN) and Mn(OAc)3 afforded tricyclic and bicyclic compounds as well as hydroxy and nitro compounds as a result of one-electron oxidation followed by carbon–carbon bond formation. This is the first example of radical cyclization (formed by one-electron oxidation) of geranyl acetone derivative 1 and its isomer 4 to give tri- and bicyclic products with carbon–carbon bond formation.

Mechanistic Aspects and Synthetic Applications of Radical Additions to Allenes

More than 50 years have passed since Haszeldine reported the first addition of a trifluoromethyl radical to an allene; in the intervening years, both the chemistry of allenes and the reactivity of single-electron species have become topics of intense interest. In this Review, we provide an overview of the fundamentals of radical additions to allenes and highlight the emergence of theoretical and experimental evidence that reveals unique reactivity patterns for radical additions to allenes as compared with other unsaturated compounds. Factors capable of exerting control over the chemo-, regio-, and stereoselectivities of the attack of carbon- and heteroatom-based radicals at each of the three potential reactive sites in an allene substrate are described. These include reaction conditions, the nature of the attacking radical, the substitution pattern of the allene, and the length of the linker between the radical center and the proximal allene carbon in the substrate. Cycloaddition reactions between allenes and partners containing π-bonds, which are likely to proceed through radical pathways, are presented to highlight their ability to rapidly access complex polycyclic scaffolds. Finally, the synthetic utility of the products arising from these chemistries is described, including their applications to the construction of complex molecules.