Rearrangement hydroxyimine

There are few examples of 1-aza-Cope rearrangements, e.g. the transformation of a-hydroxyimines 623 to aminoketones 624 in refluxing diglyme (equation 273)374. Diels-... 

The semipinacol rearrangement is not restricted to 2-heterosubstituted alcohols. Thus, the addition of diazoalkanes to ketones yields homologated ketones (equation 4), via rearrangement of the adduct (3). This process is closely related to the rearrangement of 2-amino alcohols on treatment with nitrous acid (equation 5). Similarly, 2-hydroxyimines undergo rearrangement to 2-amino ketones in a related process (equation 6). 

Certain 2-amino ketones undergo rearrangement on thermolysis to produce new 2-amino ketones. The reaction proceeds by an initial 1,2-shift to yield a hydroxyimine, followed by a second 1,2-shift to the observed product (Scheme 23). The amine must be primary or secondary and attached to a tertiary center. As would be expected, 2-hydroxyimines rearrange to 2-amino ketones (equation 40). Similarly, 2-hydroxy ketones when heated with amines form rearranged 2-amino ketones via 2-hydroxyimines (equation 41). This reaction has been applied in the synthesis of a D-ring homosteroid (equation 42). ... 

The semipinacolic rearrangement of 2-hydroxyimines has also been applied to the synthesis of 2-amino ketones which are not easily available by other methods (equation 43). ° An impressive example is the biomemetic formation of the spiroindoxyl brevianamide A (32 equation 44). ... 

Propose a mechanism for the rearrangement that converts an a-hydroxyimine into an a-aminoketone (Section 22.6). 

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