Iron-Catalyzed Ring-Opening Reactions of Cyclopropanols with Alkenes and TBHP: Synthesis of 5-Oxo Peroxides

Abstract

The ring opening of cyclopropanols is rarely used in multicomponent reactions. Herein we report the threecomponent reaction of cyclopropanols with alkenes and tert-butyl hydroperoxide (TBHP) catalyzed by an iron catalyst. This protocol enables the incorporation of both the β-carbonyl fragment and a peroxy unit across the CC double bond regioselectively, thus allowing an efficient, facile access to 5-oxo peroxides. Modification of the biologically active molecules and various downstream derivatizations of the peroxides are also demonstrated.

Orchestrating a β-Hydride Elimination Pathway in Palladium(II)-Catalyzed Arylation/Alkenylation of Cyclopropanols Using Organoboron Reagents

“…All the cyclopropanol starting materials (1a and 10a−10k) have been reported previously and were prepared as per the general procedure (vide infra). 1-(4-Methoxyphenyl)cyclopropan-1-ol (1a) 51 1-(Phenyl)cyclopropan-1-ol (10a) 51 1-(4-Methylphenyl)cyclopropan-1-ol (10b) 52 1-(2,3-Dihydrobenzo[b] [1,4]dioxin-6-yl)cyclopropan-1-ol (10c) 53 1-([1,1′-Biphenyl]-4-yl)cyclopropan-1-ol (10d) 51 1-(4-Fluorophenyl)cyclopropan-1-ol (10e) 51 1-(3,4-Difluoro)cyclopropan-1-ol (10f) 22 1-(4-Chlorophenyl)cyclopropan-1-ol (10g) 53 1-(4-Bromophenyl)cyclopropan-1-ol (10h) 53 1-(Naphthalen-2-yl)cyclopropan-1-ol (10i) 53 1-(3-Phenylpropyl)cyclopropan-1-ol (10j) 52 1-Cyclohexylcyclopropan-1-ol (10k) 51 Experimental Procedures. General Procedure for the Synthesis of Cyclopropanols (1a and 10a−10k).…”

Recent Advances in Non-Precious Metal Catalysis

“…Other notable advances in Fe-catalyzed reactions include the following publications: (1) Photoinduced iron-catalyzed ipso -nitration of aryl halides via single-electron transfer; (2) Iron-catalyzed ring-opening reactions of cyclopropanols with alkenes and TBHP: synthesis of 5-oxo peroxides; and (3) Iron-catalyzed stereoconvergent tertiary alkylation of ( E )- and ( Z ) mixed internal olefins with functionalized tertiary alkyl halides …”

Arylation of Cyclopropanol with Pyrrole: Asymmetric Synthesis of Indolizidine 167B, Indolizidine 209D, and Monomorine I

“…Addition of 3.0 equiv of radical inhibitor TEMPO or BHT into the standard reaction of 2f completely suppressed the formation of 3f , indicating this reaction might proceed through a radical pathway. On the basis of our experimental results and previous literature, a plausible mechanism was proposed (see the Supporting Information for details). Initially, oxidative ring opening of cyclopropanol with Fe(NO 3 ) 3 ·9H 2 O generated a β-keto radical, which underwent intramolecular radical addition to the π–π bond of the pyrrole unit followed by further oxidation by Fe(NO 3 ) 3 ·9H 2 O, and elimination delivered the ring-opening coupling product 3 (Scheme B).…”

“…A variety of high valence metal salts (e.g., Cu, Fe, and Mn) are capable of generating β-keto radicals from cyclopropanols. However, the electron-rich pyrrole unit is prone to be oxidized as well, which can result in complications.…”