The first enantioselective aza-Henry reaction of non-activated cyclic iminoesters, derived from cyclic amino acids, has been developed. Good yields and enantioselectivities were observed for the reactionusing our original cinchonaalkaloid sulfonamide/zinc(II) catalyst. The transition state was proposed to explain the stereoselectivity based on experiments and DFT calculations.
已经开发了衍生自环状氨基酸的非活化环状亚氨基酯的第一个对映选择性氮杂-亨利反应。使用我们的原始金鸡纳生物碱磺酰胺/锌( II ) 催化剂的反应观察到良好的产率和对映选择性。基于实验和 DFT 计算,提出了过渡态来解释立体选择性。
Synthesis of 2-acetyl-1-pyrroline, the principal rice flavor component
作者:Norbert G. De Kimpe、Christian V. Stevens、Marian A. Keppens
DOI:10.1021/jf00033a020
日期:1993.9.1
A new straightforward synthesis of 2-acetyl-1-pyrroline, the principal rice flavor component with a cracker-like flavor, is reported. The reaction sequence involves the conversion of pyrrolidine into tripyrroline, subsequent hydrocyanation of the latter into 2-cyanopyrrolidine, oxidation into 2-cyano-1-pyrroline, and Grignard addition of methylmagnesium iodide, affording an overall yield of 16-19% from pyrrolidine. In similar way, 2-propionyl-1-pyrroline, a recently discovered flavor component of popcorn, was prepared in addition to several higher analogues,i.e., 2-acyl-1-pyrrolines. Also,the synthesis of 2-(acetyl-d3)-1-pyrroline, a deuterated derivative of the rice flavor compound which is useful for the stable isotope dilution assay, is described.