Cyclododecanone, 2-hydroxy

Preparation by Ring Expansion of Cyclododecanone. Radical addition of allyl alcohol to cyclododecanone, for example, with di-/cr/-butyl peroxide as a radical initiator, yields 2-(7-hydroxypropyl)cyclododecanone. This is converted into 13-oxabicyclo[10.4.0]hexadec-l(12)-ene by acid-catalyzed dehydration [202], Addition of hydrogen peroxide, in the presence of sulfuric acid, gives 12-hydroperoxy-13-oxabicyclo[10.4.0]hexadecane. Cleavage of the peroxide by heating in xylene gives 15-pentadecanolide as well as a small amount of 15-pentadec-l l(and 12)-enolide and 12-hydroxy-15-penta-decanolide [203]. 

The procedure reported here provides a convenient method for the a-hydroxylation of ketones which form enolates under the reaction conditions. The reaction has been applied successfully to a series of para-substituted acetophenones, 1-phenyl-1-propanone, 3-pentanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclododecanone, 2-methyl cyclohexanone, 2-norbornanone and benzalacetone. In the case of a steroidal example it was shown that a carbon-carbon double bond and a secondary hydroxyl group are not oxidized. A primary amino function, as in the case of p-aminoacetophenone, is not affected.5 Similarly, a tertiary amino ketone such as tropinone undergoes the a-hydroxy at ion reaction.5... 

Radical addition of allyl alcohol to cyclododecanone and dehydrative cycli-sation gives a bicyclic dihydropyran. The ring-opening of the cyclic acetal of cyclododecanone with triisopropylaluminium and reclosure using trifluoro-methanesulfonyl anhydride provides an interesting alternative. The 15-hydroxy-pentadecanoic acid is then accessible by means of nitrosation, followed by Wolff-Kishner reduction. Apart from the reduction with hydrazine, catalytic, electrochemical and Clemmensen reduction are also well-established. 

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