Domino reactions for the synthesis of various α-substituted nitro alkenes

Abstract

Efficient one-pot methods for the synthesis of variously functionalised conjugated nitro alkenes have been reported. Despite the utility in different fields of these compounds, only a few multi-step syntheses have been reported in the literature, giving the target compounds in low overall yields. α-Nitro acrylates or cinnamates, α-nitro α,β-unsaturated ketones and, most importantly, aromatic and heteroaromatic (E)- 2-nitro allylic alcohols, compounds characterised by a well-known anticancer activity, were obtained in high yields and high diastereomeric purity by a domino condensation-dehydration process.

In Pursuit of β‐Amino‐α‐nitro‐β‐(trifluoromethyl) Ketones: Nitro‐Mannich versus Mannich‐Type Reactions

“…A hypothesis can be advanced to explain the formation of these compounds . As reported in the literature,[1b], [1c] linear α‐nitro ketones react at room temperature, without catalyst and/or solvent, with primary amines, giving the corresponding amides in good yields through cleavage of the C–C bond between the carbonyl group and the carbon–nitro moiety. Thus, the β‐amino nitro compounds observed here could derive from a very fast deacylation of the unstable nitro‐Mannich adducts, even though it cannot be completely excluded that 2d undergoes a nucleophilic substitution reaction by the primary amines formed in situ as a consequence of the imine hydrolysis favoured by the very long reaction times (3–10 d).…”

“…α‐Nitro ketones are a versatile class of α‐functionalised ketones that show an intriguing and peculiar reactivity that reflects the chameleonic nature of the nitro group . Currently, trifluoromethyl ketones are of considerable interest due to their importance as synthetic intermediates of other trifluoromethyl‐containing compounds and also due to their biological activity .…”

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

“…Other series of trials were made to improve the overall yields of the furan-bearing α-nitro esters 6n – r . We first tried to avoid the preparation of the acetals 5n or 5o and used the previously reported direct condensation between furfural ( 3n ) and ethyl nitroacetate ( 4 ) [13]. Unfortunately, we could not reproduce the 95% yield reported for compound 2n , and under a thoroughly inert atmosphere (as advised) we obtained 48–53% isolated yields at best.…”

Trifluoromethyl aldimines: an overview in the last ten years

“…The synthesis of fluorinated β-nitro amines 72 was reported by Fioravanti and co-workers, 65 through a selective ZrCl 4 -catalyzed aza-Henry reaction on trifluoromethyl (E)-aldimines.…”