A synthetic approach to 3-substituted cephalosporins: carbon-carbon bond formation at C(3) of the cephem via organocuprate chemistry
作者:Joydeep Kant
DOI:10.1021/jo00060a054
日期:1993.4
An efficient approach to the synthesis of 3-substituted cephalosporins is described. 3-Trifloxycephems readily undergo addition-elimination reactions with a variety of organocuprates to form carbon-carbon bonds at the C(3) position of the cephem nucleus. The organocuprates derived from Grignard reagents and copper(I) bromide-dimethyl sulfide complex in THF functioned most effectively in the reaction and did not promote any concurrent DELTA3/DELTA2 isomerization (a problem commonly encountered in cephalosporin chemistry). The chemistry was applied to the synthesis of a variety of 3-substituted cephalosporins bearing carbon substituents including alkyl, cycloalkyl, aryl, alkenyl, and allyl. Precursors for the synthesis of the antibiotics Cefadroxil, Cefixime, and Cefzil are also available via this route.