Stereoelectronic Substituent Effects in Polyhydroxylated Piperidines and Hexahydropyridazines

Study Based on Electronic Descriptors of the Diastereoselective Aza-Diels-Alder Cycloaddition of [(1r)-10-(N,n-Diethylsulfamoyl)isobornyl] 2h-Azirine-3-Carboxylate to E,e-1,4-Diacetoxy-1,3-Butadiene

“…It has been given a very simple operational formula in terms of the one electron energies of the frontier molecular orbital HOMO and LUMO, ε H and ε L , as: Parr et al 23 have introduced a new and useful definition of global electrophilicity, which measures the stabilization in energy when the system acquires an additional electronic charge from the environment. The electrophilicity power, ω, has been given the following simple expression: (3) in terms of the electronic chemical potential, μ, and the chemical hardness, η, defined in equations 1 and 2. The difference of this index between reactants is taken as a measure of the polarity of the cycloaddition.…”

“…[1][2][3] In this context, electrophilic chiral 2H-azirines-3-carboxylates are excellent partners in the Diels-Alder reaction expressing high reactivity, in the absence of catalysts. 4 These reactions yield fused bicyclic nitrogen-containing compounds, 4 with high biological potential, including the synthesis of iminosugars.…”

Experimental and quantum-chemical studies of anabasine complexes with copper(II) and zinc(II) ions

“…In the further parts of publication the charges are omitted for clarity. The protonation constants determined are consistent with literature data, piperidine nitrogen is more basic than pyridine nitrogen atom [23][24][25].…”

Glycosidase inhibitors: versatile tools in glycobiology

“…41 Fully unprotected derivatives 45-50 were tested as inhibitors of yeast a-glucosidase and b-glucosidase from almonds; inhibitory tests were conducted at pH 6.8 at which all of them should be largely unprotonated. 42 Inhibitory data (selected values are presented in Table 1) indicated that substitution at the 2-N position with fatty chains strongly decreased activity against a-glucosidase, suggesting that this kind of substitution disrupts interaction with the active site. Remarkably, a strong improvement in the inhibition of b-glucosidase, especially for the N-phenylpropyl derivative 50 (K i= 32 nM), was achieved.…”