α-Amino Acids andN-Protected α-Amino Aldehydes by Stereoselective Additions of a Chiral Vinyllithium Reagent to Sulfonylimines
作者:Manfred Braun、Kersten Opdenbusch
DOI:10.1002/jlac.199719970121
日期:1997.1
proven by conversion into the oxazolidinones 16a–d whose optical purity is determined to exceed 92% e.e. by 1H-NMR measurements in the presence of chiralshiftreagents. The sulfonylimine 21a and a series of para-substituted derivatives 21b–h are also allowed to react with the vinyllithium reagent 1b to give mixtures of diastereomers 22/23. The logarithms of the diastereomeric ratios 22:23 correlate with
Stereoselective synthesis of N-phenylsulfonyl substituted spiro-β-lactams
作者:Piero Dalla Croce、Concetta La Rosa
DOI:10.1016/s0957-4166(99)00096-8
日期:1999.3
A stereoselective synthesis of N-phenylsulfonyl substituted spiro-β-lactams obtained from the N-(phenylmethylene)benzenesulfonamide and the ketene valence tautomer of the bicyclic mesoionic compounds derived from 4-hydroxy substituted N-acyl-l-prolines in the presence of acetic anhydride as the dehydratingagent is presented. The reaction of (2S,4R)-4-acetyloxy or benzoyloxy-N-acyl-proline with the
reactions of amines/amides with alcohols in the past. By employing the aerobicrelayracemethodology with Pd‐catalyzed aerobicalcohol oxidation being a more effective protocol for alcohol activation, ligand‐free homogeneous palladiums are successfully used as active catalysts in the dehydrative N‐alkylation reactions, giving high yields and selectivities of the alkylated amides and amines. Mechanistic
The first nickel(0)-catalyzed [2 + 2 + 1] carbonylative cycloaddition reaction of imines and alkynes or norbornene has been achieved by employing phenyl formate as a CO source. With this method, a variety of N-benzenesulfonyl, -tosyl, and -phosphoryl-substituted γ-lactams can be prepared in good to high yields.
A Mechanochemical Zinc-Mediated Barbier-Type Allylation Reaction under Ball-Milling Conditions
作者:JieXiang Yin、Roderick T. Stark、Ian A. Fallis、Duncan L. Browne
DOI:10.1021/acs.joc.9b02876
日期:2020.2.21
A ball-milling-enabled zinc-mediatedBarbier-typeallylation reaction is reported. Notably, running the reaction in this manner renders it effective irrespective of the initial morphology of the zinc metal. The process is operationally simple, does not require inert atmospheres or dry solvents, and is reported over a range of aldehyde and ketone substrates; a gram-scale process is demonstrated.