A Rapid and Convenient Technique for converting Ketones into their Ethylenedioxy- or Trimethylenedioxy-derivatives, and for making Acetonides 

 -  Journal of Chemical Society Perkin Transation 1, p.158-160, 1979 .
<br/><br/> The ethylenedioxy-derivatives (ethylene acetals)of unhindered steroid. triterpene. and other ketones can be prepared by running a mixture of the ketone and ethylene glycol in tetrahydrofuran through an acid ion-exchange column and isolating the derivative from the eluate. This technique is particularly appropriate where such compounds are to be subjected to mass spectrometry but can also be used on a larger scale in synthetic sequences where protection of the carbonyl group is desired. The homologous (cyc!ic trimethylenedioxy-)derivatives. better for the latter purpose in certain cases. can be prepared in the same way. as can the acetonides of 1.3-dihydroxycompounds.