Diastereotopic Differentiation on Phosphorus Templates via the Ring-Closing Metathesis Reaction
摘要:
[GRAPHICS]A strategy is described in which the ring-closing metathesis reaction is utilized to desymmetrize a number of pseudo-CL-symmetric phosphorus templates 1-3. These reactions give excellent levels of selectivity (12-15:1) with vinyl phosphonamides containing a (E)-Ph group on the diastereotopic olefins. This approach is being developed as an effective method of obtaining P-chiral phosphonamides and phosphonates.
Formation of azetidines by electrophilic cyclizations have been reported, starting with homoallylic amines (4-exo mode cyclizations). We reported that the formation of these compounds can be carried out starting with allylic amines (4-endo mode cyclizations) using bis(collidine)bromonium(I) hexafluorophosphate as an electrophile. These cyclizations occur via a carbocation intermediate.
A Dual-Catalysis/Anion-Binding Approach to the Kinetic Resolution of Allylic Amines
作者:Eric G. Klauber、Nisha Mittal、Tejas K. Shah、Daniel Seidel
DOI:10.1021/ol200712b
日期:2011.5.6
A dual-catalysis approach enables the small-molecule catalyzed kinetic resolution of allylic amines by acylation. By employing 2 mol % of each 4-(pyrrolidin D)pyridine (PPY) and a readily available chiral hydrogen-bonding cocatalyst, the first nonenzymatic kinetic resolution of allylic amines was accomplished with s factors of up to 20.
Non-enzymatic acylative kinetic resolution of primary allylic amines
A non-enzymatic acetyl transfer-based kinetic resolution of primary allylic amines is reported. The process involves the use of (1S,2S)-1 in conjunction with a supported ammonium salt and affords the corresponding enantio-enriched N-acetylated allylic amines with unprecedented levels of selectivity (s-factors up to 34).
Diastereotopic Differentiation on Phosphorus Templates via the Ring-Closing Metathesis Reaction
作者:Diana S. Stoianova、Paul R. Hanson
DOI:10.1021/ol005952o
日期:2000.6.1
[GRAPHICS]A strategy is described in which the ring-closing metathesis reaction is utilized to desymmetrize a number of pseudo-CL-symmetric phosphorus templates 1-3. These reactions give excellent levels of selectivity (12-15:1) with vinyl phosphonamides containing a (E)-Ph group on the diastereotopic olefins. This approach is being developed as an effective method of obtaining P-chiral phosphonamides and phosphonates.