Sodium methoxide Diazotization

Best and Wege59have reported the first total synthesis of Mansonone F and this is described in Scheme 10. Phenol (111)60 was made to react with 2-chloroacetyl-5-methylfuran (112) in dimethylsulfoxide and sodium methoxide to yield (113). Ketalization of (113) followed by catalytic reduction and basic hydrolysis afforded anthranilic acid (114). Diazotization followed by pyrolysis with propene oxide in 1,2-dichloroethane probably yielded aryne (115), which undergoes intramolecular Diels-Alder reaction producing the adduct (116). Deoxygenation and then acid hydrolysis afforded the product (117). This was subjected to Grignard reaction. The resulting tertiary alcohol on nitration yielded the nitro compound (118) which was subjected to reduction and oxidation respectively to obtain (119). It yielded Mansonone F (120) on dehydration. 

The key intermediate for the synthesis of penthiopyrad, l-methyl-3-trifluoro-methylpyrazole-4-carboxylate 29, is prepared as shown in Scheme 11.8 by treatment of ethyl trifluoroacetate with ethyl cyanoacetate in the presence of a base such as sodium methoxide to give butenoate 27 followed by treatment of methyUiydrazine sulfate in the presence of trifluoroacetic acid. The deamination of 28 by diazotization-deazotization gives the key intermediate 29. The final steps to penthiopyrad involve amination of ester 29 with the appropriate 2-alkenyl-3-aminothiophene derivative followed by hydrogenation using a noble metal catalyst. ... 

---