Carbonylation with Carbon Dioxide

I was attracted to a paper in the February edition of SYN LETT (2009, (3), 395) wherein the authors (L Muñoz et al) report the use of carbon dioxide for the preparation of oxazolidinones from 1,2-aminoalcohols.  Some years ago I generated a significant level of an impurity in a product which arose from reaction between my substrate and carbon dioxide and since that time I have been intrigued (and wary!) by the potential reactivity of carbon dioxide.  In this paper the authors comment that there are many existing methods for the preparation of oxazolidinones such as phosgene, triphosgene, urea, dialkyl carbonates etc, but remark that many are clearly toxic and/or may require harsh reaction conditions.  There have been reports using carbon dioxide but there have still been drawbacks which the authors feel their new procedure overcomes.

The basic protocol is to react the aminoalcohol with carbon dioxide in the presence of tetramethylguanidine followed by treatment with a phosphorylating agent (either DPPA or diphenyl chlorophosphate are used in the paper) to effect the ring closure.

In conclusion, the use of carbon dioxide offers an interesting alternative to the likes of phosgene and indeed the reported procedure to ‘activate’ the carbon dioxide may well find uses in alternative chemistry where a phosgene surrogate would be advantageous.