Enantioselective reduction of aliphatic ketones using NaBH4 and TarB–NO2, a chiral boronic ester

Oxazaborolidine catalyst (CBS catalyst) has been extensively used for catalytic borane reduction with a predictable absolute stereochemistry and high enantioselectivity. However, the use of isolated CBS catalyst sometimes has the drawback of low reproducibility due to the aging of the CBS catalyst during storage. Therefore, we investigated a more reliable and practical method for the reduction of a variety of ketones including challenging substrates, primary aliphatic ketones, α,β-enones, and trifluoromethyl ketones. This review surveys the developments in borane reduction using oxazaborolidine catalysts generated in situ from chiral lactam alcohols and borane.

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ChemInform Abstract: Enantioselective Reduction of Aliphatic Ketones Using Oxazaborolidine Catalyst Generated in situ from Chiral Lactam Alcohol and Phenoxyborane.

ChemInform ◽

10.1002/chin.200947034 ◽

2009 ◽

Vol 40 (47) ◽

Author(s):

Yasuhiro Kawanami ◽

Yudai Mikami ◽

Katsuhiro Hishino ◽

Mikiko Suzue ◽

Izumi Kajihara

Keyword(s):

Enantioselective Reduction ◽

Aliphatic Ketones

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Enantioselective Reduction of Aromatic and Aliphatic Ketones Catalyzed by Ruthenium Complexes Attached to ?-Cyclodextrin.

ChemInform ◽

10.1002/chin.200516032 ◽

2005 ◽

Vol 36 (16) ◽

Author(s):

Alain Schlatter ◽

Mrinal K. Kundu ◽

Wolf-D. Woggon

Keyword(s):

Ruthenium Complexes ◽

Enantioselective Reduction ◽

Aliphatic Ketones

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Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

10.26434/chemrxiv.7130801.v1 ◽

2018 ◽

Author(s):

Haley Albright ◽

Paul S. Riehl ◽

Christopher C. McAtee ◽

Jolene P. Reid ◽

Jacob R. Ludwig ◽

...

Keyword(s):

Lewis Acid ◽

Olefin Metathesis ◽

Acid Activation ◽

Lewis Acid Catalysts ◽

Distinct Mode ◽

Aliphatic Ketones ◽

Carbon Carbon Bond ◽

Metathesis Reactions ◽

Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

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