Dihydrocodeinone oxime, Beckmann

The chemistry of such bridged naphthalenes-benzomorphans and some related compounds has been reviewed previously.<1 3) The first synthesis of a benzomorphan was achieved by Barltrop(4) however, prior to that synthesis, Schopf,(5) in his investigations of the structure of morphine, had isolated the benzomorphan, 2, from a thionyl chloride-induced, second-order Beckmann rearrangement of dihydrocodeinone oxime, 1. Reinvestigation(5a,5b) of the Beckmann rearrangement and a study of the Schmidt reaction of 6-oxomor-phinans confirmed Schopf s work and led to the isolation of the anticipated lactam (2a). 

Schopf sought to obtain direct evidence for the location of the side-chain at C-13 by subjecting dihydrocodeinone oxime to a Beckmann transformation, when, if the side-chain is located at C-13 [liv], an aldehyde [lv] would be the product, whereas if the point of attachment is C-14 [lvi] a ketone [lvii] would be formed. Neither the oxime nor its methyl ether yielded the desired proof directly, and it was only after a sequence of further degradations that the conclusion was drawn that the product was [lv], indicating C-13 as the point of attachment of the side-chain [85] (see Chap. X). 

Beckmann Transformation The Beckmann transformation of dihydrocodeinone oxime was investigated by Schbpf [68] in an attempt to determine the point of attachment of the carbon end of the ethanamine side-chain. If the point of attachment is C-13 [xliv] the product of transformation should be ail aldehyde [xi.v], whoroas if it is C-5 [xltx] the product should bo a... 

R + R = CH2O), which upon lithium aluminium hydride reduction provided (120 R = OH, R = Me). On the other hand, treatment of dihydrocodeinone with methyl-lithium yielded the epimer( 120 R = Me, R = OH). ° The Beckmann rearrangement of dihydrocodeinone oxime (120 R -f R = NOH) gave the c-homo-6-azamorphinan (121) whereas the Schmidt reaction of dihydrothebainone afforded the phenol (122). ° ° ... 

---