A high-performance enantioselective quaternary ammonium hypoiodite catalysis was developed for the dearomatization of arenols using oxone as an environmentally benign oxidant. The oxidation of not only 1- and 2-naphthols but also phenols, which were hardly reactive using the previous hypoiodite catalysis, readily proceeded under mild conditions, and only inorganic wastes were generated from the oxidant used. Control experiments and Raman analysis revealed the in situ generation of I+ such as hypoiodous acid as an unstable active species and molecular iodine (I2) as a stable dormant species. Most of the advantages of the present I+/oxone catalysis, compared to previous I+/(H2O2 or ROOH) systems, may result from generation of the stable dormant state and the higher reactivity of catalysts under acidic conditions.
We developed a practical and environmentally benign method for the chlorinative dearomatization of arenols using transient electrophilic chlorinating species generated in situ from inexpensive sodium chloride and Oxone as a Cl source and oxidant, respectively, under mild conditions. Moreover, the regioselective chlorination or chlorinative dearomatization of 1‐naphthols was also achieved by changing the reaction conditions.
We developed a chemoselective oxidative dearomative spiroetherification and spiroamination of arenols using I + /oxone catalysis. The intramolecular dearomative C− O and C−N couplings proceeded much more efficiently under slightly acidic conditions to give the corresponding spiro adducts in higher yields compared with previous methods using transition metal or hypervalent iodine catalysts. Control experiments suggested that both hypoiodous acid and iodine might be active species for these reactions.
Compounds containing one or more stereogenic phosphorous atoms in the P(V) oxidation state are important to chemistry, biology and medicine. These include marketed antiviral drugs such as Tenofovir alafenamide and Remdesivir, an effective treatment for Ebola which has also recently been approved for use against SARS-CoV-2 in the US. Existing approaches for the stereoselective synthesis of P-stereogenic centers, while elegant, remain mostly diastereoselective, with catalytic enantioselective approaches being limited in application. Accordingly, conceptually novel, broad-scope, catalytic strategies for the efficient stereoselective synthesis of diverse stereogenic P(V) containing compounds remain essential. To this end, we describe a novel enantioselective two-stage strategy, exploiting a catalytic and highly enantioselective desymmetrisation of phosphonate esters. Pivoting on the first stereocontrolled, sequential nucleophilic substitution of enantiotopic leaving groups from readily accessible pro-chiral P(V) precursors, a bifunctional iminophosphorane (BIMP) superbase catalyst was found to be essential in delivering reactive desymmetrised intermediates capable of downstream enantiospecific substitution. This uniquely modular, catalytic platform allows broad-scope, stereoselective access to a diverse library of chiral P(V) compounds including those with O, N and S-linkages.
Compounds containing one or more stereogenic phosphorous atoms in the P(V) oxidation state are important to chemistry, biology and medicine. These include marketed antiviral drugs such as Tenofovir alafenamide and Remdesivir, an effective treatment for Ebola which has also recently been approved for use against SARS-CoV-2 in the US. Existing approaches for the stereoselective synthesis of P-stereogenic centers, while elegant, remain mostly diastereoselective, with catalytic enantioselective approaches remaining limited in application. Accordingly, conceptually novel, broad-scope, catalytic strategies for the efficient stereoselective synthesis of diverse stereogenic P(V) containing compounds remain essential. To this end, we describe a novel enantioselective two-stage strategy, exploiting the first catalytic and highly enantioselective desymmetrisation of phosphonate esters. Pivoting on the stereocontrolled, sequential nucleophilic substitution of enantiotopic leaving groups from readily accessible pro-chiral P(V) precursors, a bifunctional iminophosphorane (BIMP) superbase catalyst was found to be essential in delivering reactive desymmetrised intermediates capable of downstream enantiospecific substitution. This uniquely modular, catalytic platform allows broad-scope, stereoselective access to a diverse library of chiral P(V) compounds including those with O, N and S-linkages.
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