Acetophenone with ethylmagnesium

Acetophenone oxime reacts with ethylmagnesium bromide to give the dihydro-1,2-oxazine (118) and this with nitrous acid affords 3,5-diphenyl-6//-1,2-oxazine (119). The proposed mechanism en route to the initial product is complex, but there seems no reason why this synthesis could not be extended to other analogues (Scheme 48) (67T3505). 

In 1964, thanks to the development of modern techniques, especially electron-spin resonance (ESR), a direct proof could be given of the occurrence of radicals in the reaction of Grignard reagents, such as ethylmagnesium iodide, phenylmagnesium bromide, and /Jflra-tolylmagnesium bromide, in tetrahydrofuran (THF) with aromatic ketones, such as 4-chlorobenzophenone, 4-aminobenzophenone, 4-methoxybenzophenone, 4,4 -dimethoxybenzophenone, acetophenone, and 4-bromoacetophenone [34]. 

---