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Nicolai Cramer

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Publications associées (117)

Alkynyl triazenes enable divergent syntheses of 2-pyrones

Kay Severin, Nicolai Cramer, Jin Fay Tan, Carl Thomas Bormann

The 2-pyrone motif occurs frequently in bioactive natural products and is appreciated as synthetic intermediates. However, only few methods allow for diversifying functional group modifications on this relevant heterocycle. The distinct properties of 1-alk ...

2021

Society and Chemistry They Are a-Changin'

Paul Joseph Dyson, Nicolai Cramer

2021

Catalytic Reduction of Oximes to Hydroxylamines: Current Methods, Challenges and Opportunities

Nicolai Cramer

Catalytic reduction of oximes represents a direct efficient approach to synthesize valuable hydroxylamine derivatives. However this transformation presents significant challenges: oximes are hard to reduce and, if reactive, reductive cleavage of the weak N ...

WILEY-V C H VERLAG GMBH2021

Modular Chiral N-Heterocyclic Carbene Ligands for the Nickel-Catalyzed Enantioselective C-H Functionalization of Heterocycles

Nicolai Cramer, Johannes Diesel

N-Heterocyclic carbenes (NHCs) are the ligands of choice in a large variety of transformations entailing different transition metals. However, the number and variety of chiral NHCs suitable as stereo-controlling ligands in asymmetric catalysis remains limi ...

2020

1,3,2‐Diazaphospholenes Catalyze the Conjugate Reduction of Substituted Acrylic Acids

Nicolai Cramer, John Henry Reed

The potent nucleophilicity and remarkably low basicity of 1,3,2- diazaphospholenes (DAPs) is exploited in a catalytic, metal-free 1,4-reduction of free ,-unsaturated carboxylic acids. Notably, the reduction occurs without a prior deprotonation of the car ...

Wiley-VCH Verlag2020

Cobalt(III)‐Catalyzed Enantioselective Intermolecular Carboamination by C−H Functionalization

Nicolai Cramer, Kristers Ozols, Shunsuke Onodera

Wiley-VCH Verlag GmbH2020

Alkynyl Triazenes as Fluoroalkyne Surrogates: Regioselective Access to 4-Fluoro-2-pyridones by a Rh(III)-Catalyzed C–H Activation–Lossen Rearrangement–Wallach Reaction

Kay Severin, Nicolai Cramer, Jin Fay Tan, Carl Thomas Bormann

Fluorinated pyridones are an important scaffold displaying relevant biological activities. Efficient assembly strategies of pyridones are transition metal-catalyzed C–H annulations with alkynes. The inaccessibility and extreme lability of fluoro alkynes re ...

2020

Iridium-catalyzed acid-assisted asymmetric hydrogenation of oximes to hydroxylamines

Nicolai Cramer

Asymmetric hydrogenations are among the most practical methods for the synthesis of chiral building blocks at industrial scale. The selective reduction of an oxime to the corresponding chiral hydroxylamine derivative remains a challenging variant because o ...

American Association for the Advancement of Science2020

Enantioselective Iron-Catalyzed Cross-[4+4]-Cycloaddition of 1,3-Dienes Provides Chiral Cyclooctadienes

Nicolai Cramer, Elena Braconi

Chiral cyclooctadienes are a frequently occurring scaffold in natural products and specialty chemicals, and are used as ligands in asymmetric catalysis. Accessing substituted cyclooctadienes in an efficient asymmetric fashion has been notoriously challengi ...

2020

Intermolecular Palladium(0)-Catalyzed Atropo-enantioselective C-H Arylation of Heteroarenes

Nicolai Cramer, Qui-Hien Nguyen

Atropisomeric (hetero)biaryls are motifs with increasing significance in ligands, natural products, and biologically active molecules. The straightforward construction of the stereogenic axis by efficient C-H functionalization methods is extremely rare and ...

2020

Catalytic Enantioselective Functionalizations of C-H Bonds by Chiral Iridium Complexes

Nicolai Cramer, Qui-Hien Nguyen, Jin Fay Tan, Adrien Jules Louis Madron Du Vigné

The development of catalytic enantioselective transformations, enabling the construction of complex molecular scaffolds from simple precursors, has been a long-standing challenge in organic synthesis. Recent achievements in transition-metal catalyzed enant ...

2020

Asymmetric (CpRh)-Rh-x(III)-Catalyzed Acrylic Acid C-H Functionalization with Allenes Provides Chiral gamma-Lactones

Nicolai Cramer, Shouguo Wang

A chiral cyclopentadienyl (Cp-x) ligand featuring the semi-saturated H8-binaphthyl backbone as the chiral element was developed. Its application potential was demonstrated by (CpRhIII)-Rh-x-catalyzed C-H bond functionalization of acryl acids and allenes, e ...

AMER CHEMICAL SOC2020

A Chiral Naphthyridine Diimine Ligand Enables Nickel‐Catalyzed Asymmetric Alkylidenecyclopropanations

Nicolai Cramer, Elena Braconi

A novel class of chiral naphthyridine diimine ligands (NDI*) readily accessible from C2‐symmetric 2,6‐di‐(1‐arylethyl)anilines is described. The utility of these ligands, particularly one with fluorinated aryl side arms, is demonstrated by a reductive Ni‐c ...

Wiley-VCH Verlag GmbH2020

Enantioselective (CpRhIII)-Rh-x-Catalyzed Carboaminations of Acrylates

Nicolai Cramer, Coralie Danielle Annick Duchemin

Enantioselective carboaminations of olefins constitute an attractive strategy for a rapid increase in molecular complexity from readily available starting materials. Reported here is an intermolecular asymmetric carboamination of acrylates using rhodium(II ...

Wiley-VCH Verlag GmbH2020

Accessing Monosubstituted Cyclopentadienyl Rhodium(I) and Iridium(I) Complexes by a Simultaneous Nucleophilic Addition-Metalation Approach to Fulvenes

Nicolai Cramer, Aragorn Nathan Laverny

Despite advances in the synthesis of polysubstituted cyclopentadienyl metal complexes, the rapid access to a library of monosubstituted Cp bearing metal complexes remains challenging. A convenient and general method to access a broad range of monosubstitut ...

2020

Rhodium(III)-Catalyzed Cyclopropane C-H/C-C Activation Sequence Provides Diastereoselective Access to alpha-Alkoxylated gamma-Lactams

Nicolai Cramer, Benoît Daniel Bertrand Audic

A Cp*Rh(III)-catalyzed C-H/C-C bond activation sequence of cyclopropyl hydroxamates has been developed. The three-component process allows trapping of the intermediate rhodacycle with diazomalonates and an alcohol nucleophile to provide access to synthetic ...

AMER CHEMICAL SOC2020

Stay positive: catalysis with 1,3,2-diazaphospholenes

Nicolai Cramer, John Henry Reed, Johannes Klett

P-Hydrido 1,3,2-diazaphospholenes (DAPs) are a class of nucleophilic molecular hydrides capable of addition to a variety of substrates. They can be turned over with terminal reductants and emerged over the last few years as powerful and versatile catalysts ...

2020

Efficient Kinetic Resolution of Sulfur-Stereogenic Sulfoximines by Exploiting (CpRhIII)-Rh-X-Catalyzed C-H Functionalization

Nicolai Cramer, Marcus Brauns

Chiral sulfoximines with stereogenic sulfur atoms are promising motifs in drug discovery. We report an efficient method to access chiral sulfoximines through a C-H functionalization based kinetic resolution. A rhodium(III) complex equipped with a chiral Cp ...

Wiley-VCH Verlag GmbH2019

Rh-I, Ir-III ,and Co-III Complexes with Atropchiral Biaryl Cyclopentadienyl Ligands: Syntheses, Structures, and Catalytic Activities

Nicolai Cramer, Gints Smits, Coralie Danielle Annick Duchemin

Chiral cyclopentadienyl (Cp-x) group 9 metal complexes have become versatile catalysts for a variety of efficient enantioselective C-H functionalizations. Atropchiral binaphthyl-derived Cp-x ligands having tuning options at the 3,3'-positions present a rob ...

2019

Generation of Heteroatom Stereocenters by Enantioselective C-H Functionalization

Nicolai Cramer, Johannes Diesel

C-H functionalization has been established as an efficient way to generate molecular complexity. The formation of stereogenic carbon atoms by asymmetric C-H functionalization has seen tremendous progress over the past decade. More recently, the direct cata ...

2019

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