Copper(II) Complexes of the Tetraazamacrocyclic Tertiary Amide Ligand Alanyl‐Cyclam

Abstract

Hydrogen bonding to the electrically neutral tertiary carboxamide nitrogen atom of peptidyl‐prolyl groups is known to facilitate the C–N bond rotation during peptide and protein folding. Since metal complexes with nitrogen‐coordinated tertiary amide ligands are formally analogous, they may be used to model this so‐called electrophilic activation. In this paper we report on the synthesis of a monoacylated cyclam complex, [(Boc‐Ala‐cyclam)Cu](CF3SO3)2 (8; Boc: tert‐butyloxycarbonyl, Ala: alanine, cyclam: 1,4,8,11‐tetraazacyclotetradecane). It contains a fully sp3‐hybridized metal‐bound amide nitrogen atom. The resonance is completely cancelled and the observed C–N distance of 147 pm is consistent with a single bond. These features are exceptional among Werner‐type complexes and define the maximal possible electrophilic distortion of an amide bond.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Novel Monocyclam Derivatives as HIV Entry Inhibitors: Design, Synthesis, Anti‐HIV Evaluation, and Their Interaction with the CXCR4 Co‐receptor

“…Flash chromatography was performed using silica gel 35-70 mm (SDS, 2000027). Compounds 9, 10, [21] and 12 [20] were synthesized by previously described methods. Compound 5 (1.26 g, 2.0 mmol) and 7 (0.44 g, 3.0 mmol) were dissolved in MeOH (15 mL) in a microwave vessel, Na 2 SO 4 was added, and the vessel was sealed.…”

Effective Methods for the Biotinylation of Azamacrocycles

“…Our other concern with an amide linker centered on the unpredictable nature of its interaction with a metal center. Not only are structurally authenticated Werner complexes of tertiary amides extremely rare, , but the mode of the tertiary amide nitrogen−metal interaction is difficult to predict, even in closely related systems, , which could reduce the stability and/or change the properties of the coordination complex, thus limiting our ability to detect a binding event of our macrocycle−biotin conjugate in a predictable and reproducible manner. We thus sought to introduce hydrolytically robust alkyl pendant arms.…”

6,7,9,10-Tetrahydro-16,22-ethanooxyethano-5,8,11,19-tetraoxa-16,22-diazadibenzo[h,q]cyclooctadecine-17,21-dione: a benzylannelated macrobicyclic diamide

“…(2008). E64, o2003 [doi:10.1107/S1600536808030067] 6,7,9,10- 8,11,q] Cryptands (Dietrich et al, 1969;Lehn, 1973) and tertiary amides (Tummler et al, 1977;Niklas et al, 2004;Schickaneder et al, 2006) are of interest as hosts for cationic guests. The title compound, (I), was isolated during the synthesis of the corresponding benzoannelated cryptand.…”