Butyric anhydride, from oxidation

In all these reactions, acetic anhydride is a convenient and effective reagent, but it is not unique benzoic228a and butyric anhydride ia have been used. As mentioned earlier (p. 234), from these reactions of picoline oxides small amounts of pyridones and 3-hydroxypyridines have sometimes been isolated. 

Condensation of the allylic alcohol 646 with methyl orthopropionate in butyric acid gave ester 647 which, after hydrolysis, was treated with methyllithium to give ketone 648. Fischer indole cyclization with poly-phosphoric acid of the phenylhydrazone of 648 gave the indole 649. The iV-oxide of 649 in trifluoroacetic anhydride at 0° gave in 92% yield the hexahydroellipticine 650, convertible with palladium-charcoal to 267 in 35% yield. The overall yield from 646 is on the order of 19% (Scheme 43). 

---