Malonaldehyde is a very useful building block in organic syn- thesis. Of particular interest are its monoacetals, as they allow for sequential use of the aldehyde groups at selected steps of the syn- thetic pathway. Few methods of general applicability are reported in the literature for the preparation of malonaldehyde monoacetals, which were reviewed by Botteghi and Soccolini'). Owing to the need for various monoacetals of malonaldehyde in our research