To improve the supramolecular properties of organic compounds, chemists continuously need to identify new tools. Herein, the influence of the stereoselectiveinsertion of halogen atoms (F or Cl) on different supramolecular properties is analyzed. Inserting anti-halohydrins in polyols considerably strengthens the H-bonding networks and other supramolecular interactions. This behavior resulted in improved
Enantioselective α-Chlorination of Aldehydes with Recyclable Fluorous (S)-Pyrrolidine-Thiourea Bifunctional Organocatalyst
作者:Chun Cai、Wei Zhang、Liang Wang、Dennis Curran
DOI:10.1055/s-0029-1219198
日期:2010.2
A novel fluorous (S)-pyrrolidine-thiourea bifunctional organocatalyst is prepared. The catalyst shows good activity and enantioselectivity for direct α-chlorination of aldehydes using N-chlorosuccinimide (NCS) as the chlorine source. It can be recovered from the reaction mixture by fluorous solid-phase extraction with excellent purity for direct reuse.
The direct organocatalytic enantioselective α-chlorination of aldehydes has been developed. The reaction proceeds for a series of different aldehydes with NCS as the chlorine source using easily available catalysts such as l-proline amide and (2R,5R)-diphenylpyrrolidine. The α-chloro aldehydes are obtained in up to 99% yield and up to 95% ee. The synthetic utility of the enantioselective α-chlorination
Enantioselective Synthesis of Spiroacetals via Silver(I)-Promoted Alkylation of Hemiacetals: Total Synthesis of Cephalosporolides E and F
作者:Stanley Chang、Robert Britton
DOI:10.1021/ol302694s
日期:2012.12.7
A silver(I)-promoted intramolecular hemiacetal alkylation has been developed that converts readily available keto-chlorodiols into functionalized spiroacetals containing 5,5-, 5,6-, and 5,7-membered ring systems. The efficiency of this process is demonstrated in a concise total synthesis of the fungal metabolites cephalosporolides E and F.