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Abstract
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The regioselective hydrolysis of ketenimines derived from NH-acids, such as 2,2,2-trichloro- N-phenylacetamide or ethyl-2-anilino-2-oxoacetates and acetylenic esters in the presence of tert-butyl isocyanide in a THF=H2O system (1=1) without any catalysis leads to a diastereomeric mixture of dialkyl 2-[(tert-butylamino)carbonyl]-3-[(2,2,2-trichloroacetyl) anilino]succinates and dialkyl 2-[(tert-butylamino) carbonyl]-3-[2-ethoxy-2-oxoacetyl)anilino]- succinates in good yields. Dynamic NMR effects were observed in the 13C NMR spectra of diethyl 2-[(tert-butylamino)carbonyl]-3-[(2,2,2-trichloroacetyl) anilino]succinate as a result of restricted rotation around the N-aryl single bond. The free energy of activation (G#) for this process is 37.9 kJmol1 which leads to an observable atropisomerism.
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