Die kristalline und molekulare Struktur von cis-Coleon D,einem cis-A/B-6,7-Diketo-abietan-Derivat

The Crystal and Molecular Structure of cis-Coleon D, a cis-A/B-6,7-Dioxo Derivative of Abietane. The X-ray analysis of cis-Coleon D ( 1 ) confirmed the postulated position of H? C(5) in the plane of the neighbouring keto group. This situation is unfavourable for enolisation, in contrast to the situation where the H? C(5) is perpendicular to the keto plane, as supposed in trans-Coleon D ( 2 ). The α-diketone moiety has a significant (P)-helicity of about 10 (1)°. The acentric crystal structure of cis-Coleon D was determined by direct methods and refined with 1533 structure amplitudes to R = 0.042. The absolute configuration was determined from the known chirality of the A/B-ring junction.