A novel method for the efficient synthesis of methyl 2-oxo-2-arylacetates and its application to the preparation of fungicidal methyl (E)-O-methyloximino-2-arylacetates and their (Z)-stereoisomers
作者:Renzo Rossi、Adriano Carpita、Piergiorgio Pazzi、Luisa Mannina、Daniela Valensin
DOI:10.1016/s0040-4020(99)00632-8
日期:1999.9
Methyl 2-oxo-2-arylacetates 1, which include some fluorinated compounds, have been synthesized in moderate to excellent yields by reaction of methyl oxalyl chloride with arylzinc halides in the presence of Pd(PPh3)4. The highest yields have been obtained when these reactions involved arylzinc bromides which were prepared by conversion of the corresponding aryl bromides to organolithiums, followed by
甲基-2-氧代-2- arylacetates 1,其中包括一些氟化化合物,已在由温和的甲基草酰氯与在Pd的存在下芳基锌卤化物(PPH反应合成优异的产率3)4。当这些反应涉及芳基溴化锌时,可获得最高的收率,该芳基溴化锌是通过将相应的芳基溴化物转化为有机锂,然后用ZnBr 2进行金属转移来制备的。通过用O处理,化合物1已经高产率地转化为相应的(E)-和(Z)-O-甲基氧亚氨基-2-芳基乙酸酯吡啶中的-甲基羟胺盐酸盐。通过MPLC在硅胶上轻松分离化合物,并通过NMR技术确定其结构和立体化学。如此制备的通式5的化合物包括农业化学上重要的杀真菌剂,即其氟化的结构类似物,以及被证明能够延迟从变质纸中分离的真菌种类的生长的化合物。有趣的是,几种通式(Z)-5的化合物在日光和催化量的碘的存在下进行了部分立体突变。