Titanium(III)-mediated synthesis of a 1,2,3-tricarbonyl moiety from an .alpha.-oximido-.beta.-keto ester: application to the synthesis of the carbacephem nucleus
摘要:
A general procedure for the conversion of alpha-oximido-beta-keto esters into vicinal tricarbonyl moieties by TiCl3 in aqueous, buffered (pH 5) conditions with acetone cosolvent was demonstrated. As applied to N-hydroxy beta-lactam 17, which contained an alpha-oximido-beta-keto ester side chain, these combined reductive and hydrolytic conditions effected simultaneous tricarbonyl formation and beta-lactam N-O bond reduction. Vicinal tricarbonyl-containing N-unsubstituted beta-lactam 18 was a direct precursor to semifunctionalized carbacephem 1.
Mn(III) promoted N-O bond reduction of N-hydroxy-2-azetidinones
作者:Arun Ghosh、Marvin J. Miller
DOI:10.1016/s0040-4039(00)60063-1
日期:1993.1
Treatment of various N-hydroxy-2-azetidinones with Mn(III) acetate unexpectedly afforded the corresponding reduced N-unsubstituted-2-azetidinones in the presence of hydrogen donor solvents.
Functionalization of the .beta.-lactam ring: diastereoselective azide transfer and nitrogen-oxygen bond reduction on C4 substituted N-hydroxy-.beta.-lactams in one step
作者:Catherine M. Gasparski、Min Teng、Marvin J. Miller