Intermediates in the synthesis of camptothecin and related compounds and synthesis thereof
The present invention provides a short, convergent total synthesis of camptothecin and related compounds which consists of a novel 4+1 radical annulation. The present invention also provides novel chemical intermediates for such 4+1 radical annulations.
1. A chemical compound having the formula
wherein R 9 is a normal alkyl group or a branched alkyl group and wherein R 10 is —CHO or —CH 2 OCH 2 CH═CHR 11 , wherein R 11 is an alkyl group, a vinyl group, an ethynyl group or a phenyl group, wherein R 12 , R 13 and R 14 are independently an alkyl group or an aryl group, and wherein X is I or Br.
2. A chemical compound having the formula
wherein R 9 is a normal alkyl group or a branched alkyl group, wherein R 4 is an alkyl group, an allyl group, a propargyl group or a benzyl group and wherein R 12 , R 13 and R 14 are independently an alkyl group or an aryl group.