Oxirane derivatives

The chiral oxirane derivative 185 (R = 4-BrCgH4CH2) and vinylmagnesium bromide yield the allylic amine 186 allylmagnesium bromide reacts in an analogous fashion192. 

Amides [41,44], thioamides [41 ] and amidines [45] are converted into nitriles by the reaction with dichlorocarbenes generated by Makosza s procedure (Table 7.16). Under similar conditions, monosubstituted and A.A-disubstituted ureas are converted into cyanamides (Table 7.17) JV,(V -disubstituted ureas produce carbodi-imides in low yield [41,46,47]. /V-Carbamoyl derivatives of dibenzo[/ /]diazepines and the related 10, l l-oxirane derivatives are converted into the corresponding... 

In contrast to the foregoing observations, there are other reactions that generate oxirane derivatives as intermediates that undergo further transformations to a variety of compounds. For example, oxidation of ketenes 15 gives polyesters 17 via the intermediacy of oxiranones 16. The conversion 15 16 probably involves a nucleophilic attack of oxygen end of the... 

Other examples include conversion of ketones to a-hydroxydimethylace-tals 1 (Scheme la), which result from a nucleophilic ring opening of the intermediate oxiranes 18 by methoxide ions, as shown in Scheme 10. Interestingly, it is possible to isolate such oxirane derivatives in a few cases such as that shown in Eq. (7) (85S326). 

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