Developing asymmetric iron and ruthenium-based cyclone complexes; complex factors influence the asymmetric induction in the transfer hydrogenation of ketones
The oxidoreductases Lactobacillus brevis alcohol dehydrogenase (LBADH) and Candida parapsilosis carbonyl reductase (CPCR) are suitable catalysts for the reduction of ketones to afford enantiopure sec. alcohols. A broad variety of alkynones (1, 3, and 5) are accepted as substrates and the corresponding propargylic alcohols (2, 4, and 6) are obtained in good yield and excellent enantiomeric excess. By
Merging Asymmetric [1,2]-Additions of Lithium Acetylides to Carbonyls with Type II Anion Relay Chemistry
作者:Kevin T. O’Brien、Amos B. Smith
DOI:10.1021/acs.orglett.9b02959
日期:2019.9.20
union of a variety of lithium acetylides and electrophiles exploiting an achiral linchpin via an anionic reaction cascade. This Type II AnionRelayChemistry tactic is initiated via an enantioselective [1,2]-carbonyl addition exploiting BINOL catalysis to access an enantioenriched alkoxide intermediate. Migration of charge across the linchpin via a [1,4]-Brook rearrangement with electrophile capture
Propargyl aza-Claisenrearrangement of 4-propargylaminoisoxazoles 1 proceeded in the presence of cationic gold(I) catalysts to give 4-amino-5-allenylisoxazoles 2 in good to high yields. The silyl group at the terminal alkyne and a cationic gold(I) catalyst bearing a sterically bulky ligand are essential for the generation of isolable allene intermediates. The N-protection of the generated 4-amino-5-allenylisoxazoles
Improved Method for the Synthesis of β-Carbonyl Silyl-1,3-Dithianes by the Double Conjugate Addition of 1,3-Dithiol to Propargylic Carbonyl Compounds
作者:Sumit Mukherjee、Dimitra Kontokosta、Aditi Patil、Sivakumar Rallapalli、Daesung Lee
DOI:10.1021/jo901950e
日期:2009.12.4
Base-mediated double Conjugate addition of 1,3-propane dithiol to various silylated propargylic aldehydes and ketones allows for an efficient and scalable synthesis of beta-carbonyl silyl-1,3-dithianes.
Asymmetric Hydrogenation of Alkynyl Ketones with the η<sup>6</sup>-Arene/TsDPEN–Ruthenium(II) Catalyst
Enantioselective hydrogenation of alkynyl ketones catalyzed by Ru(OTf)(TsDPEN)(eta(6)-p-cymene) (TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine) affords the propargylic alcohols in up to 97% ee. The alkynyl moieties are left intact In most cases. The reaction can be conducted with a substrate-to-catalyst molar ratio as high as 5000 under 10 atm of H-2. The mode of enantioselection is elucidated with the transition state models directed by the CH/pi attractive interaction between the substrate and the catalytic species.