Herein we report a dramatic acceleration of the lipase-catalyzed kinetic resolution of atropisomeric 1,1 0biaryl-2,2 0 -diols by the addition of sodium carbonate. This result likely originates from the increased nucleophilicity of the phenolic hydroxyl group toward the acyl-enzyme intermediate. Under these conditions, various substituted C 2 -symmetric and non-C 2 -symmetric binaphthols and biphenols were efficiently resolved with $50% conversion in only 13-30 h with excellent enantioselectivity.
Cross-dehydrogenative coupling between 3-hydroxycarbazoles and 2-naphthols has been achieved by using a mesoporous silica-supported oxovanadium catalyst.
The enzymatic acylative desymmetrization of σ‐symmetric 2'‐halo‐1,1'‐biphenyl‐2,6‐diols was achieved for the first time using commercially available Burkholderia cepacia lipase immobilized on diatomaceous earth to give (S)‐mono esters. The hydrolytic desymmetrization of the corresponding diacetates was also achieved using the same lipase to give (R)‐mono esters. Our results, therefore, demonstrate that a single lipase can conduct the enantiodivergent synthesis of axially chiral biphenyl compounds in high chemical and optical yields.
More than 50 years after the original Mitsunobu reaction reported in 1967, its catalytic and redox neutral reactions have been developed. While the conventional method has problems such as the laborious separation of by products and the explosive nature of azo reagents, the redox neutral method solves these problems and its catalytic method enabled water as a sole by product. This article describes the recent developments in the redox neutral Mitsunobu reactions.
The Cover Feature shows an image for the enantiodivergent synthesis of axially chiral biphenyls from σ‐symmetric 1,1'‐biphenyl‐2,6‐diol derivatives by single lipase‐catalyzed acylative and hydrolytic desymmetrization. The background picture, so‐called “Upside‐down Fuji” or “Sakasa Fuji” in Japanese, is one of the most spectacular views of Mt. Fuji. Reflecting Fuji upon a nearby lake generates its mirror image or enantiomer, creating an overall beautiful symmetry. More information can be found in the Full Paper by S. Akai et al.
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