An efficient method for targeting a variety of symmetrical and asymmetrical α-substituted dithiomalonates (DTMs) is described, utilizing 1H-imidazole-1-carbothioates as reactive acylating agents and MgBr2⋅OEt2/DBU or LiHMDS for soft or hard enolization conditions of thioesters, respectively. The utility of this methodology was demonstrated through the synthesis of the pyridopyrimidine mesoionic insecticides:
Various thiolesters are prepared in good yields by the reaction of thiols with acyloxypyridinium salts formed in situ from free carboxylic acids and 2-fluoro-1-methylpyridinium p-toluenesulfonate.
THE DIASTEREOSELECTIVE ADDITION OF TIN(II) ENOLATES DERIVED FROM CARBOXYLIC THIOESTERS TO α-IMINOESTER
作者:Teruaki Mukaiyama、Hiroshi Suzuki、Tohru Yamada
DOI:10.1246/cl.1986.915
日期:1986.6.5
The diastereoselective addition of the Sn(II) enolatesderivedfrom carboxylic thioesters to α-iminoester is described. The Sn(II) enolates of t-butylthiol esters react smoothly with α-iminoester to afford the corresponding β-aminoacid derivatives in good yield with high diastereoselectivity.