Synthesis of Alkyl Citrates (−)-CJ-13,981, (−)-CJ-13,982, and (−)-L-731,120 via a Cyclobutene Diester
作者:Liselle Atkin、Zongjia Chen、Angus Robertson、Dayna Sturgess、Jonathan M. White、Mark A. Rizzacasa
DOI:10.1021/acs.orglett.8b01665
日期:2018.7.20
from a cyclobutene diester is presented. The key sequence involves a formal [2 + 2]-cycloaddition of a silylketene acetal with dimethylacetylene dicarboxylate to provide the cyclobutene diester 14 with 4.5:1 stereoselectivity. Exposure of diester 14 in acidic methanol effected a hydrolysis, intramolecular oxy-Michael reaction, and cyclobutanone methanolysis cascade to give the triester 15. Iodination
提出了一种从环丁烯二酯中提取柠檬酸烷基酯天然产物的高效且经济的新方法。关键序列包括甲硅烷基乙烯酮缩醛与二甲基乙炔二羧酸酯的正式[2 + 2]-环加成,以提供具有4.5:1立体选择性的环丁烯二酯14。将二酯14暴露于酸性甲醇中会发生水解,分子内氧基-迈克尔反应和环丁酮甲醇分解级联反应,从而产生三酯15。然后进行碘化和消除,得到了关键的柠檬酸烷基酯烯烃中间体,将其转变为天然产物(-)-CJ-13,982(1),(-)-CJ-13,981(2)和(-)-L-731,120(3)通过交叉复分解和随后的还原。