Four 5-nitrofuryl polyene aldehydes (I, n= 1 to 4) were prepared stepwise from 5-nitrofurfural by repeated condensation with methyl vinyl ether in the presence of boron trifluoride etherate. This method gives considerably better yields than aldol condensation with acetaldehyde. Evidence is presented that the intermediates in this reaction are 1J-dioxanes (11). Oximes, semicarbazones, thiosemicarbazones and aminoguanidine derivatives of ...
