Elusive 2-aminofuran Diels–Alder substrates for a straightforward synthesis of polysubstituted anilines

Abstract

The first multicomponent coupling of isocyanides, α,β-unsaturated carbonylic compounds and dienophiles, based on the trapping of unstable intermediate 2-aminofurans, is described. This novel tandem [4 + 1]-[4 + 2] cycloaddition is efficiently catalysed by yttrium triflate and constitutes an operationally simple and highly convergent approach to a variety of polysubstituted anilines. Moreover, this methodology permits the use of tert-butylisocyanide as a convertible isocyanide to yield directly N-unprotected anilines in the same pot.

Regioselective Tandem [4 + 1]–[4 + 2] Synthesis of Amino-Substituted Dihydroxanthones and Xanthones

“…In order to evaluate our synthetic methodology toward the construction of the basic skeleton of more complex xanthone natural products, dimeric chromone 11 was synthesized from readily available bisphenol (8) and transformed to dimeric dihydroxanthone 12. Thus, according to Scheme 3, acetylation and acid catalyzed Fries rearrangement 14 led almost quantitatively to 1,1′-(4,4′-dihydroxy-[1,1′-biphenyl]-3,3′-diyl)bis-(ethan-1-one) (9), 15 which was readily transformed into bischromone 11, via the corresponding double enaminone (10).…”

An easy synthesis of diversely functionalized 2H-chromenes and amido amines by an enol-Ugi reaction

“…In fact, although this classical reaction is a powerful strategy for the synthesis of α-amido amides, deacylation of Ugi adducts usually requires harsh conditions that lead to mixtures of products. 26 Aminoamides are interesting synthetic targets, since they possess useful therapeutic properties. 13,27 Thus, development of simple straightforward and flexible syntheses of unprotected α-amino amides is still a challenging task.…”

Tuning the Reactivity of Isocyano Group: Synthesis of Imidazoles and Imidazoliums from Propargylamines and Isonitriles in the Presence of Multiple Catalysts

“…Intramolecular nucleophilic addition of the amidine nitrogen atom to the silver-coordinated triple bond through a 5-exo-dig mode afforded the intermediate 12, which upon dealkylation (R = tBu), would produce 13 and TfOH. [29] Protonation of 13 followed by double-bond isomerization would produce 3 with the concurrent regeneration of AgOTf. We stress that alternative cyclization of 10 to 14 [30] and its isomerization product 15, resulting from the normal carbene-like reactivity of isonitrile, was not isolated, probably because of the rapid metathesis of the CÀYb bond.…”

“…Intramolecular nucleophilic addition of the amidine nitrogen atom to the silver-coordinated triple bond through a 5-exo-dig mode afforded the intermediate 12, which upon dealkylation (R = tBu), would produce 13 and TfOH. [29] Protonation of 13 followed by double-bond isomerization would produce 3 with . the concurrent regeneration of AgOTf.…”