Oxaspiro hexanes synthesis

The reaction involving the alkylation of p-hydroxyalkyl selenides to give p-hydroxyalkylselenonium salts which are then cyclized with a base is by far the most general. It allows Ae synthesis of a large variety of epoxides such as tenninal, a,a- and a,p-disubstituted, tri-33-> and tetra-substituted, 3,i88 as oxaspiro[2.0.n]-hexanes, -heptanes and -octanes (Scheme 161, g Scheme 162, d Scheme 164, d Scheme 165, b) - and vinyl oxiranes (Schemes 166 and 181)33 -239 from both p-hydroxy-alkyl methyl33- 3 3 22>.222j36,263 phenyl selenides. ... 

The wide applicability of the cyclopropanation reaction allows the preparation of intermediates for elaborated compounds. The preparation of trans- and cw-l-phosphoryl-5-oxo-4-oxaspiro[2.3]hexanes 1, which are important intermediates for the synthesis of heterocycles or functionalized cyclopenten-l-ones, illustrates well the potential of this reaction. 

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