Crystal structure of 2-N,N-diethylamino-1-carbomethoxy-2a,8a-dihydro-2a-methoxycyclobuta [b]naphthalene-3,8-dione, C₁₉H₂₁NO₅

Abstract

Crystals of the ‘title’ compound, C₁₉H₂₁NO₅, are monoclinic, space groupP2₁/c,a = 7·706,b = 14·470,c = 16·836 Å, β = 106·45°,Z = 4. The structure was determined with CuKα diffractometer data by symbolic addition procedures and Fourier syntheses, and was refined by full-matrix least-squares methods toR = 0·079 for 2192 observed reflexions. All non-methyl hydrogen atom positions were determined. The non-aromatic six-membered ring has aboat conformation. The four-membered ring, which iscis-fused to the six-membered ring, is slightly folded, and the planar amino and carboxyl groups lie almost in the four-membered ring plane. This geometry, and the detailed bond distances suggest electron delocalization, which may make the compound a useful intermediate in the synthesis of a stable cyclobutadiene system.