MOLECULAR AND CRYSTAL-STRUCTURE OF 7-CARBOXY-3,4,7-TRIMETHYLNORCAR-3-ENE

The first X-ray single crystal diffraction study of the care-3-ene der ivative -7-carboxy-3,4,7-trimethylnorcar-3-ene-showed this molecule ad opted syn-boat conformation with the methyl substituent in the cyclopr opane ring being equatorial and carboxy-group being axial. Steric fact ors like the eclipsed position of the hydrogen atoms at C1 and C2 in a nti-boat conformation and the steric repulsion of substituents in posi tion 7 of the bicycle with cis-cyclohexene fragment in syn-boat form a s well as intermolecular O-H...O hydrogen bonding were supposed to be responsible for the structure observed in the crystalline phase. (C) 1 997 Elsevier Science B.V.