Ready Access to Fluorinated Phosphonate Mimics of Secondary Phosphates. Synthesis of the (α,α-Difluoroalkyl)phosphonate Analogues of <scp>l</scp>-Phosphoserine, <scp>l</scp>-Phosphoallothreonine, and <scp>l</scp>-Phosphothreonine
作者:David B. Berkowitz、MariJean Eggen、Quanrong Shen、Richard K. Shoemaker
DOI:10.1021/jo9604752
日期:1996.1.1
rate (16, 85%), and the Garner ester derived from D-serine (15, 77%). Expeditious treatment of the resultant alpha,alpha-difluoro-beta-keto phosphonates with hydride or Grignard reagents followed by alcohol deoxygenation provides a general method for the synthesis of (alpha,alpha-difluoroalkyl)phosphonate analogues of secondary phosphates. For tertiary alcohols, Dolan-MacMillan deoxygenation conditions
除了先前记录的二乙基硫代(二氟甲基)膦酸酯(8)与伯三氟甲磺酸酯和醛的反应外,我们在此报告8与官能化但未活化的甲酯反应,可进行有效的酰基取代。因此,8与以下甲酯(产物,收率)完全反应(-78摄氏度,THF):(S)-异亚丙基甘油甘油酯(14,99%),(S)-3-O-(叔丁基二甲基甲硅烷基) )-2-O-四氢吡喃基甘油酸酯(16,85%),和衍生自D-丝氨酸的加纳酯(15,77%)。用氢化物或格氏试剂快速处理所得的α,α-二氟-β-酮膦酸酯,然后进行醇脱氧,为合成仲磷酸盐的(α,α-二氟烷基)膦酸酯类似物提供了一种通用方法。对于叔醇,采用Dolan-MacMillan脱氧条件。通过改进的方法获得必需的草酸甲酯,其中受阻叔醇的醇锂在低温下不可逆地生成,然后与草酰氯甲基缩合。相对立体化学是通过将Garner酯衍生的Boc-氨基醇转化为相应的环状六元膦酸酯并检查其(1)H NMR光谱确定的。通过