Efficient syntheses of new chiral peptidomimetic macrocycles through a configurationally driven preorganization

Organogel–quantum dots hybrid materials displaying fluorescence sensitivity and structural stability towards nitric oxide

“…In this context, pseudopeptidic compounds are good receptors of anions due to the coordination properties of the amide groups [2,3]. For this purpose, the preorganization provided by macrocyclic structures is important, and the preparation of such structures from C 2 pseudopeptidic bis(amidoamines) has been investigated in detail in our research group [4][5][6][7]. Previous studies focused on compounds such as 1 (Scheme 1) [4].…”

NMR Studies of Optically Active Schiff Bases

“…42,44 For the optically active Schiff bases [24], [25] in CDCl 3 , the d 15 N values were in the range from À 65.2 to À 230.3 ppm and increased for the following series of derivatives: salicylaldehyde < 3-bromosalicylaldehyde < 5-nitrosalicylaldehyde < 4,6-dimethoxy-salicylaldehyde < 2-hydroxynaphthaldehyde which resulted from increased mole fraction of the NH-form. 12 OH N R 1 R 2 R 3 [24] OH N Ph R 1 R 2 R 3 [25] Formation of the adduct with dirhodium complex [6] has significantly changed the chemical shift of the compounds in which proton transfer occurred, for example, for the adduct of N-(5-nitrosalicylidene)-2-aminobutane, the chemical shift was À 198.2, which was shielded by of 110 ppm in comparison to that in the starting Schiff base. 12 The large signal shift was due to the shift of the proton transfer equilibrium towards NH tautomer.…”

“…The intense NOESY effects between protons of naphthyl and alkyl units have proved the anti-configuration of the major stereoisomer. Chiral Schiff bases are intermediates in the synthesis of peptidomimetic macrocycles which have been studied in detail by Bru et al 24 and Alfonso et al [9]. 25…”

“…On the basis of the data for N-(2-hydroxynaphthylidene)-L-leucine methyl ester, it was shown that the presence of bifurcated hydrogen bond and the interaction between COO À and NH stabilised the proton transferred form [27]. Deuterium isotope effects in CDCl 3 have been applied in studies of proton transfer equilibrium for optically active Schiff bases [24], [25] as well as their dirhodium tetracarboxylate adducts. 11 The DC-2(D) values were in the range from þ 541 to À 546 ppb for imines and from þ 524 to À 255 ppb for their adducts.…”

Observations on the Influence of Precursor Conformations on Macrocyclization Reactions

“…folding of oligoamides, 15 synthesis of cycloparaphenylens, 16 and peptidomimetic macrocycles. 17 In order to address the dearth of novel macrocyclic scaffolds for screening campaigns, we have undertaken a research program aimed at developing methods for facile synthesis of macrocycles from simple precursors. 18,19 In the course of these investigations, we have produced acyclic diols and tested their propensity to undergo macrocyclization, choosing the formation of sulfites as a representative reaction.…”