Mechanistic investigations into a novel C-O bond construction process.

We have recently described a new family of hydroxylamine reagents which are effective for the α-functionalisation of carbonyl compds. Scheme 1 shows the proposed mechanistic course of this transformation. Reaction of a carbonyl compd. 1 with the hydroxylamine reagent 2 leads to an iminium ion 3 which converts to the enamine 4 under the reaction conditions. [3,3]-Sigmatropic rearrangement of this enamine followed by in situ hydrolysis of the resulting α-oxyimine 5 leads directly to the obsd. product 6 in good to excellent yield. With the aim of making this methodol. more efficient, extending the applicability of the protocol and to obtain a fundamental insight, we have undertaken a detailed investigation into the kinetics and mechanism of the transformation. This has principally comprised reaction monitoring by NMR, HPLC and LCMS, together with a decompn. study on the reagent 2. This talk will describe our principal findings in unraveling the mechanism of this fascinating reaction. [on SciFinder(R)]