Ketones, spirocyclic => phenols

The selenium version of this reaction offers the advantages that over-oxidation is no problem and that the elimination of the selenoxides occurs at room temperature or below so that the oxidation and elimination normally occur as a single step.23 A simple example is the preparation of another starting material 158 for a dienone-phenol rearrangement.24 The lithium enolate of spirocyclic ketone 155 reacts with PhSeCl to give 156 and oxidation with H202 gives the dienone 158 directly, with the selenoxide 157 as an intermediate. The overall yield is 83%. 

The first total syntheses of the marine bromotyrosine-derived alkaloid subereamollines A and B were also described by Ley s group in 2011 [119]. Access to the spirocyclohexadienylisoxazoline core of the targets was ensured by a DIB-mediated oxo-spirocyclization of the phenolic oxime methyl ester 205, followed by a diastereoselective ketone reduction of the resulting orf/io-quinol 206 (Fig. 51). The methyl ester 207 was then converted in two steps into rac-subereamolline A or B. Both racemates were then separated into their respective enantiomers by chiral HPLC [119]. 

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