Interaction of 2-Naphthol with γ-Ureidoacetals. A New Method for the Synthesis of 2-Arylpyrrolidines

One-Pot Synthesis of Novel Dibenzoxanthenes, Diarylbutanes, and Calix[4]resorcinarenes via Consecutive Pyrrolidine Ring-Closure/Ring-Opening Reactions

“…However, according to NMR data, in this case the yield of target dibenzoxanthenes 5a,c appeared to be rather low. e main products were previously described by us 2naphthylpyrrolidine derivatives 1a,c [24] (Scheme 2). Next, we gradually increased the amount of trifluoroacetic acid used.…”

“…e most general approach to these compounds is the acidic media condensation of electron-rich aromatic nucleophiles with aldehydes [17][18][19] or acetals [20][21][22] (Scheme 1(A)). However, this method is inapplicable in case of acetals containing urea moiety, since these compounds are subject to intramolecular cyclization in acidic media [23][24][25][26]. Earlier, we have developed the approach to diarylbutanes, dibenzoxanthenes, and calixarenes possessing urea fragment via acid-catalyzed ring opening of 2-(2hydroxynaphthalene-1-yl)pyrrolidine-1-carboxamides 1 [27,28] (Scheme 1(B)).…”

Acid‐Catalyzed Cascade Reaction of 4‐Aminobutanal Derivatives with (Hetero)aromatic Nucleophiles: A Versatile One‐Pot Access to 2‐(Hetero)arylpyrrolidines.

“…Inspired by this work, we developed a method of synthesis of 2-arylsubstituted N-carbamoylpyrrolidines 4 based on trifluoroacetic acid-catalyzed reaction of N-(4,4-diethoxybutyl) (thio)ureas 3 with aromatic nucleophiles (Scheme 3). [25][26][27][28][29] The reaction proceeds in mild conditions, and both aliphatic and aromatic substituents in ureas 3 are tolerated.…”

“…Probably it is the different solubility of diastereomers in chloroform and solvents used for compounds purification, which affects a diastereomeric ratio. Similarly, a reaction of compounds 8 having two N- (4,4-diethoxybutyl)urea moieties connected via polymethylene or 1,4-phenylene spacer give diastereomeric bis(2-aryl)pyrrolidines 9 (Scheme 3).. [25][26][27] The synthetic outcome of a reaction of bis(ureas) 8 with resorcinol derivatives depends on a structure of starting compound and reaction conditions (Scheme 5). [38,39] The reaction of urea 8 possessing hexamethylene spacer with two equivalents of resorcinol, 2-methylresorcinol, or pyrogallol in chloroform, benzene, or acetone in the presence of trifluoroacetic acid failed to produce the desired compounds.…”

Synthesis of functionalized diarylbutane derivatives by the reaction of 2-methylresorcinol with γ-ureidoacetals

“…(4,4-Diethoxy)ureas IIa-IId were prepared from commercially available 4,4-diethoxy-1-butanamine I. Synthesis of compounds IIa-IIc has been previously described [9,10]; compound IId was prepared by reacting 4,4-diethoxy-1-butanamine I with N,Ndimethylcarbamoyl chloride in the presence of triethylamine (Scheme 1).…”