Intramolecular Cycloaddition of the Azomethine Ylides Derived from α-Amino Acids or Esters and 5-Oxo-6-heptenals or 4-Oxo-5-hexenals
作者:Shuji Kanemasa、Kenji Doi、Eiji Wada
DOI:10.1246/bcsj.63.2866
日期:1990.10
Intramolecularcycloadditions of the azomethine ylides bearing a carbonyl-activated olefinic moiety, generated from α-amino acids or esters and 5-oxo-6-heptenals or 4-oxo-5-hexenals, produce the stereoselective internal cycloadducts either to olefin or carbonyl dipolarophilic function with normal or inverse regioselectivity, depending upon the types of ylides as well as the intervening chain length
An effective synthesis of (E)-4-oxo-5-hexenals 6 and the acetals 5 starting from ethyl 2-alkoxy-1-cyclopropanecarboxylates 1a-d is presented. The acid-induced ring opening of the cyclopropanecarboxylates 1a, b, followed by phosphorylmethylation or the phosphorylmethylation of the ester 1c followed by ring opening leads to the 5-acetal of 2,5-dioxopentylphosphonate 4. The Horner-Emmons olefination of 4 with various aldehydes produces the title compounds.