Amine oxides and alkyl halides

The orientational behaviour of amine oxide pyrolyses has been adequately summarised by Cope and TrumbulE . As for the acetate decompositions, orientation in the simple alkyl systems is controlled primarily by statistical factors but departure from this influence is noted with the bulky r-butyl substituent and the acid strengthening beta phenyl substituents Eclipsing effects are greater in the planar five-membered transition states than in the puckered six systems and this is borne out by the greater preference for trans-olefin formation from amine oxides than esters and xanthates (152, cf. 149). 

With increasing size of substituents, a greater tendency for trans- rather than di-olefin formation should be exhibited and this is found to be the case as dimethylamine oxides of the larger alicyclic rings give mainly the trans isomer. 

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