Search

We present a novel deoxygenation method for heterocyclic Noxides utilizing iodide as a catalyst. Iodide acts as a reducing catalyst that is regenerated by formic acid, which also serves as a Brønsted activator and solvent. The method demonstrates high efficiency and excellent selectivity in the reduction of a variety of heterocyclic N-oxides and tertiary amines. Our computational DFT investigation revealed that the reduction mechanism entails a direct interaction between iodide and the oxygen of the N-oxide within a Mg2+/formic acid framework, resulting in the formation of the N-heterocycle and the release of a hypoiodite unit. Additionally, a molecular mechanism for the regeneration of iodide from hypoiodite, facilitated by formic acid, is suggested. This method provides an environmentally friendly approach for the deoxygenation of N-oxides and related species. [ABSTRACT FROM AUTHOR]

Ethyl cyanoformate and methyl cyanoformate (Mander's reagent) are both routinely used to perform C-selective ketone alkoxycarbonylations. Interestingly, both reagents were found to yield oxoalkenenitriles through an unprecedented deoxycyanation of 1,3-dicarbonyl compounds (e.g., 2-methylcyclohexane-1,3-dione). Although this method is not general, this is the first time that both Mander's reagent and ethyl cyanoformate have been used for the deoxycyanation of 1,3-dicarbonyl compounds for the preparation of synthetically useful oxoalkenenitriles. Limitations on the substrate scope of the present method are discussed. [ABSTRACT FROM AUTHOR]

In the last two decades, the field of photoredox catalysis (PRC) has grown impressively with reports of new synthetic methodologies and more efficient versions of known free-radical reactions. The impressive success of visible-light-mediated photoredox catalysis is, in great part, due to its low environmental impact, mild reaction conditions, clean reactions, and inexpensive methodologies. These features have allowed photoredox catalysis to emerge as a powerful tool in the synthesis of natural products; much excellent work was reported between 2011 and 2015. Since 2016, a number of more efficient and impressive total syntheses of natural products featuring photoredox catalysis have been reported. In this review, we summarize the recent synthetic applications of photoredox catalysis in the total synthesis of natural products between 2016 and 2020. 1 Introduction 2 Intermolecular Additions from Functionalized Substrates 2.1 Intermolecular Additions from Alkyl Halides 2.2 Intermolecular Additions from Alcohols and Carboxylic Acids 3 Cyclizations from Functionalized Substrates 3.1 Cyclizations of Carbon-Centered Radicals 3.2 Cyclizations of Nitrogen-Centered Radicals 4 Intramolecular Cyclization from Non-functionalized N–H Bonds 4.1 Type I Radical Cascade 4.2 Type II Radical Cascade 4.3 Type III Radical Cascade 5 Functionalization of Imines and Enamines 6 Cycloadditions 7 Miscellaneous 7.1 Dehalogenation and Reductive Decarboxylation 7.2 Thiyl Radical Promoted Cascade 8 Conclusions and Perspectives [ABSTRACT FROM AUTHOR]