4‐Methoxy‐3‐penten‐2‐one

Abstract

4‐Methoxy‐3‐penten‐2‐one product: 4‐methoxy‐3‐penten‐1‐one

Synthesis of 1,2,3-Triazoles by Cycloadditions of Azides with Enol Ethers

“…[27][28][29][30] Similarly, enol ethers used are available either commercially or by published procedures. [31][32][33] Since alkenes of enol ethers are less electron-rich than enamine alkenes, they react less quickly than enamines in azide cycloadditions. 10 To increase the cycloaddition rate, the azide-enol ether cycloadditions were performed at 200 °C in a sealed tube without solvent.…”

“…The products of azide-enol ether cycloadditions incorporate functional groups that are amenable to further derivatization of the triazole products. 27 trans-2-azidocyclohexanol (5c), 28 ethyl 2azidoethanoate (5a), 29 benzyl azide (5d), 27 N-(2-azidoethyl)phthalimide (5f), 30 and 4-azidomethyl-2,2-dimethyl-1,3-dioxolane (5e), 31 1-methoxycyclohexene (8c), 32 and 4-methoxypent-3-en-2-one (8d) 33 were prepared according to literature procedures. All other reagents were purchased from commercial sources and used without purification.…”

Platform approach to diversification: bio-based methyl coumalate to functionalized aromatics via a Diels-Alder strategy

“…30 In general, preparations of 24b entail protecting the corresponding alcohol which is only commercially available from very few suppliers and is a simple functional group manipulation which does not construct the aromatic The second carbonyl functionality could also be achieved by converting 2,4-pentanedione to 4-methoxypent-3-en-2-one 23da by an acid-catalyzed procedure. 32 Surprisingly, exclusive formation of 24d was observed when 23da was subjected to the established Diels-Alder conditions, which was confirmed by 1 H NMR data with a singlet at 3.77 ppm for the methylene protons adjacent to the aromatic ring. Presumably, the thermal environment facilitates isomerization of 23da to the less sterically hindered 23db dienophile which more readily participates in the ensuing reaction sequence.…”

“…Vinyl ether 4-methoxypent-3-en-2-one (23da) was prepared according to the procedure of Kraus and Krolski. 32 Ketals 39e, 39f-h, 74a, and 78d and vinyl ethers 23h, 74b, and 78c were prepared according to the procedure of Cooper. 86 Ketals 39b and 39d were prepared by the method of Harris,45 while acetal 39i was prepared according to the protocol by Ritter.…”

“…With geometrically constrained s-cis conjugated alkenes, 2-pyrones are preorganized dienes for the Diels-Alder reaction. [32][33][34] However, since 2-pyrones are partially aromatic compounds, thermal conditions or activation are generally needed, which is further supplemented by appropriate substitution to tune the electronics for more optimal reactivity. Diels and Alder reported the first reaction of the 2-pyrone methyl coumalate (13) with maleic anhydride (14) in 1931 35 to obtain the corresponding adduct 15, but in only 30% yield (Scheme 2).…”