α,β‐Unsaturated Aldehydes in the Synthesis of Five‐Membered Heterocyclic Compounds with One Heteroatom: Recent Advances from Developments in Metal‐ and Organocatalysis

Abstract

The ever-increasing interest in the chemistry of five-membered heterocyclic compounds is due to their paramount importance in such essentialf ields as pharmacology, medicine, biology,o rganic synthesis of fine chemicals, agricultural chemistry,a nd the chemical industry.T his Review summarizesa nd highlights methodsf or the synthesis of five-membered O-, N-, and S-heterocycles based on transformations of a,b-enals. Over the last decade, these reactions, which often differ from the processes involving other a,bunsaturated carbonyl compounds in methodology andr esults, have been gathering momentum. Many of the catalytic and technological novelties discussed in the review,s uch as asymmetricm etal-and organocatalysis, multiple catalysts, one-pot multicomponent reactions proceeding through domino,c ascade, or tandem reactions, andm icrowave activation, promote the formation of diverset arget products, the structures of which becomes clear from the mechanistic schemesg iven in the review.T he mechanisms discussed reflect great advances in the chemo-, regio-, and stereoselectivity of the reactions with participation of a,b-alkenals, achieved in the last 15 years, which allowsn ew five-membered heteroarenes and related compounds (pyrroles, dihydropyrroles, pyrrolidines,f urans, thiophenes) to be synthesized.

New atranes and similar ionic complexes. Synthesis, structure, properties

“…We have developed an expedient stereoselective method for the synthesis of original α,β‐unsaturated aldehydes, ( Z )‐2‐alkoxy‐ and ( Z )‐2‐alkylthio‐3‐(het)arylpropenals (Het)ArCH=C (YR)C(H) = O (Ar = phenyl, furyl, pyridinyl, etc. ; Y = O, S), by the condensation of (het)aryl‐containing aldehydes with 2‐alkoxy‐ and 2‐alkylthioacetaldehydes . The obtained α,β‐unsaturated aldehydes are highly reactive compounds attracting significant theoretical and practical interest.…”

“…The obtained α,β‐unsaturated aldehydes are highly reactive compounds attracting significant theoretical and practical interest. For example, they were used in the synthesis of various heterocycles and drugs …”

“…; Y = O, S), by the condensation of (het)aryl-containing aldehydes with 2-alkoxy-and 2-alkylthioacetaldehydes. [73][74][75][76] The obtained α,β-unsaturated aldehydes are highly reactive compounds attracting significant theoretical [77] and practical [78] interest. For example, they were used in the synthesis of various heterocycles and drugs.…”

An efficient and enantioselective Michael addition of aromatic oximes to α,β‐unsaturated aldehydes promoted by a chiral diamine catalyst derived from α,α‐diphenyl prolinol

“…In 2010, Pihko's group reported the enantioselective Michael reaction of aromatic oximes to α , β ‐unsaturated aldehydes catalyzed by α , α ‐diaryl prolinol silyl ether to obtain the addition products, which rapidly cyclized into stable isoxazoline under acidic conditions with good to excellent enantioselectivities. In those reactions, aromatic oximes are good nucleophiles and α , β ‐unsaturated aldehydes are good Michael receptors . We envisioned that the diamine catalysts, bearing α , α ‐diphenyl prolinol silyl ether and diamine catalysts, would catalyze aromatic oximes and α , β ‐unsaturated aldehydes with good results.…”

“…In those reactions, aromatic oximes are good nucleophiles 43 and α,β-unsaturated aldehydes are good Michael receptors. 44 We envisioned that the diamine catalysts, bearing α,α-diphenyl prolinol silyl ether and diamine catalysts, would catalyze aromatic oximes and α,β-unsaturated aldehydes with good results. To our knowledge, diamine catalysts derived from α,α-diphenyl prolinol have not drawn enough attention on asymmetric organocatalysis yet.…”