Brochu Michael P, Brown Sean P, MacMillan David W C
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA.
J Am Chem Soc. 2004 Apr 7;126(13):4108-9. doi: 10.1021/ja049562z.
The first direct enantioselective catalytic alpha-chlorination of aldehydes has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective chlorination of aldehydes to generate alpha-chloro aldehydes, an important chiral synthon for chemical and medicinal agent synthesis. The use of imidazolidinone 3 as the asymmetric catalyst has been found to mediate the halogenation of a large variety of aldehyde substrates with the perchlorinated quinone 1 serving as the electrophilic chlorinating reagent. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. The capacity of catalyst 3 to override the inherent bias of resident stereogenicity in the chlorination of enantiopure beta-chiral aldehydes is also described. Catalyst quantities of 5 mol % were generally employed in this study.
醛的首例直接对映选择性催化α-氯化反应已经完成。烯胺催化的应用为醛的对映选择性氯化生成α-氯醛提供了一种新的有机催化策略，α-氯醛是化学和药物合成中一种重要的手性合成子。已发现使用咪唑啉酮3作为不对称催化剂，以全氯醌1作为亲电氯化试剂，可介导多种醛底物的卤化反应。在这种新的有机催化转化中，也能兼容多种醛底物。还描述了催化剂3在对映纯β-手性醛的氯化反应中克服固有立体异构性偏向的能力。本研究中一般使用5 mol%的催化剂量。
