mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β-substituted nitrocompounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized
Opposite Enantioselectivity in the Bioreduction of (<i>Z</i>
)-β-Aryl-β-cyanoacrylates Mediated by the Tryptophan 116 Mutants of Old Yellow Enzyme 1: Synthetic Approach to (<i>R</i>
)- and (<i>S</i>
)-β-Aryl-γ-lactams
作者:Elisabetta Brenna、Michele Crotti、Francesco G. Gatti、Daniela Monti、Fabio Parmeggiani、Robert W. Powell、Sara Santangelo、Jon D. Stewart
DOI:10.1002/adsc.201500206
日期:2015.5.26
The Trp 116mutants of OldYellowEnzyme1 that catalyse the reduction of (Z)‐β‐aryl‐β‐cyanoacrylates give the oppositeenantioselectivity according to the nature of the amino acid in position 116. Small amino acids (e.g., alanine) make the substrate bind to the enzyme′s active site in a “classical” orientation, affording the (S)‐enantiomer of the reduced product. When the size of the amino acid increases
Catalytic Asymmetric Synthesis of Secondary Nitriles via Stereoconvergent Negishi Arylations and Alkenylations of Racemic α-Bromonitriles
作者:Junwon Choi、Gregory C. Fu
DOI:10.1021/ja303442q
日期:2012.6.6
α-alkyl substituents; the first examples of the use of alkenylzinc reagents in stereoconvergent Negishi reactions of alkyl electrophiles; demonstration of the utility of a new family of ligands for asymmetric Negishi cross-couplings (a bidentate bis(oxazoline), rather than a tridentate pybox); in the case of arylzincreagents, carbon-carbon bond formation at a remarkably low temperature (-78 °C), the lowest
A short, chemoenzymatic route to chiral β-aryl-γ-amino acids using reductases from anaerobic bacteria
作者:Anna Fryszkowska、Karl Fisher、John M. Gardiner、Gill M. Stephens
DOI:10.1039/b919526b
日期:——
A short chemoenzymatic synthesis of β-aryl-γ-aminobutyric acids has been developed, based on a highly enantioselective biocatalytic reduction of β-aryl-β-cyano-α,β-unsaturated carboxylic acids.
With the assistance of hydrogen bonds, the first asymmetric hydrogenation of β-cyanocinnamic esters is developed, affording chiral β-cyano esters with excellent enantioselectivities (up to 99% ee). This novel methodology provides an efficient and concise synthetic route to chiral GABA-derivatives such as (S)-Pregabalin, (R)-Phenibut, (R)-Baclofen. Interestingly, in this system, the catalyst with a
在氢键的帮助下,首次开发了 β-氰基肉桂酸酯的不对称氢化,提供了具有优异对映选择性(高达 99% ee)的手性 β-氰基酯。这种新的方法为手性 GABA 衍生物(如 ( S )-普瑞巴林、( R )-Phenibut、( R )-巴氯芬)提供了一种有效且简洁的合成途径。有趣的是,在该体系中,单氢键供体催化剂的性能优于双氢键供体,这是金属有机催化领域的一个新发现。