| Summary: | Catalytic enantioselective conjugate additions of organometallic reagents to electron-deficient alkenes and asymmetric allylation of carbonyl compounds are important reactions for the construction of new carbon-carbon bonds. However, a method using an allylnickel species to perform catalytic nucleophilic allylation enantioselectively remains considerably underdeveloped and only a handful of examples have been described. In this thesis, enantioselective nickel-catalyzed arylative and alkenylative intramolecular allylations of allenyl electrophiles with boronic acids are described.
Enantioselective nickel-catalyzed arylative intramolecular 1,4-allylations
An asymmetric nickel-catalyzed desymmetrization of allenyl cyclohexa-2,5-dienones by reaction with arylboronic acids is reported. In this study, nucleophilic allylnickel species, formed by nickel-catalyzed arylation of the allene, undergo 1,4-allylation-cyclization reaction to furnish hexahydroindol-5-ones and hexahydrobenzofuran-5-ones with three contiguous stereocenters in high diastereo- and enantioselectivities (87−99% ee).
Enantioselective nickel-catalyzed arylative and alkenylative intramolecular 1,2-allylations
An asymmetric nickel-catalyzed cascade reaction of allenyl ketones with boronic acids is described. In this project, a nickel-catalyzed arylation and alkenylation of the allene gives allylnickel species, which undergo a 1,2-allylation-cyclization with tethered ketones to furnish 3-hydroxypyrrolidin-2-ones, 3-hydroxypyrrolidines and 4-hydroxypiperidines in high diastereo- and enantioselectivities.
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