Analysis of the 1 H NMR spectrum of 5-nitrofurfural in methanol-d 4 (Fig. ), on looking more closely, together with electron deficiency of the furan ring in 5-nitrofurfural despises any S E Ar reaction, and suggests formation of hemiacetal 3 and/or acetal 4. It is unlikely that the reaction of methanol-d x with 5-nitrofurfural resulting in acetal 4 such that even though the -OCD 3 moieties in 4 are chemically equivalent, they are, in point of fact, anisochronous by virtue of the furan ring current. Thus, probably, almost certainly, two signals from the -OCD 3 moieties in 4 should be observed in its C NMR spectrum which is not the case, so it is very likely that the product be hemiacetal 3 (Fig. ). As depicted in Fig. Intriguingly, 1 H NMR spectra of 5-nitrofurfural in CDCl 3 and DMSO-d 6 did not differ much in terms of the overall pattern of signals (Fig. ).