TY - JOUR TI - A highly efficient synthesis of 3-methylcholanthrene AU - Thanasis Gimisis AU - Masato Koreeda JO - The Journal of Organic Chemistry PY - 1993 VL - 58 TODO - 25 SP - 7158--7161 PB - American Chemical Society (ACS) SN - null TODO - 10.1021/jo00077a045 TODO - null TODO - A five-step synthesis of 3-methylcholanthrene (1) has been achieved starting from 5-methylhomophthalic anhydride and N,N-diethyl-1-naphthamide in 55% over all yield. Treatment of a solution of the preformed lithium enolate of 5-methylhomophthalic anhydride (3) with an equimolar solution of 2-lithio-1-naphthamide (4), followed by acid hydrolysis, provides cleanly the spirobislactone 5 in 80% overall yield. In addition, the synthesis features a unique, highly selective double Friedel-Crafts cyclization of the aryl diacid 2 with PPA to give rise, after acetylation, to keto acetate 6. ER -