The first general methodology for the gram-scale preparation of previously overlooked β-(hetero)aryl-α-nitro-α,β-enals (
3) is reported. Condensation of (hetero)aromatic aldehydes with 2-nitroethanol gave the
E-isomers of uncommon β-(hetero)aryl-α-hydroxymethyl-α,β-unsatured-nitroalkenes (
2), as determined by NOE and X-ray studies. α-Nitro-α,β-enals
3 were subsequently obtained by hypervalent iodine oxidation of
2 as
E−
Z-mixtures in solid form. They showed varied stability and solvent-dependent thermal-promoted and photopromoted
E−
Z interconversion. Starting with furfural, experimental conditions were developed to prepare the corresponding nitroenal
3a enriched in either the
E or the
Z isomer:
E-
3a/
Z-
3a ≈ 90/10 and 20/80, respectively. In contrast with other structurally related compounds, nitroenals
3 have their (hetero)aryl-vinyl unit and their formyl and nitro groups all in a planar arrangement, both in solid form and in solution; accordingly, they are colored compounds with predicted high dipole moments. As deduced from solution-NMR and X-ray data, the C
C and the C
O double bonds in
3 are exclusively
s-
cis-oriented; this disposition corresponds in fact to the DFT-computed most stable conformer.
