cis‐(6RS,13RS)‐3,3,10,10‐Tetramethyl‐6,13‐diphenyl‐1,8‐dioxa‐4,11‐diazacyclotetradecane‐2,5,9,12‐tetraone and two of its precursors |
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Authors: | Anthony Linden Boyan Iliev Heinz Heimgartner |
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Abstract: | The title macrocycle, C26H30N2O6, (VI), was obtained by `direct amide cyclization' from the linear precursor 3‐hydroxy‐N‐[1‐methyl‐1‐(N‐methyl‐N‐phenylcarbamoyl)ethyl]‐2‐phenylpropanamide, the N‐methylanilide of rac‐2‐methyl‐2‐[(3‐hydroxy‐2‐phenylpropanoyl)amino]propanoic acid, C13H17NO4, (IV). The reaction proceeds via the intermediate rac‐2‐(2‐hydroxy‐1‐phenylethyl)‐4,4‐dimethyl‐1,3‐oxazol‐5(4H)‐one, C13H15NO3, (V), which was synthesized independently and whose structure was also established. Unlike all previously described analogues, the title macrocycle has the cis‐diphenyl configuration. The 14‐membered ring has a distorted rectangular diamond‐based [3434] configuration and intermolecular N—H⋯O hydrogen bonds link the molecules into a three‐dimensional framework. The propanoic acid precursor forms a complex series of intermolecular hydrogen bonds, each of which involves pairwise association of molecules and which together result in the formation of extended two‐dimensional sheets. The oxazole intermediate forms centrosymmetric hydrogen‐bonded dimers in the solid state. |
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