Inhaltszusammenfassung

The reaction of alpha,beta-unsaturated imines, derived from steroidal amines and cinnamaldehyde, with carbon monoxide and ethylene leads to the formation of steroids with a 1,3-dihydropyrrol-2-one ring system attached to the D-ring or the steroid. In addition, a new stereogenic center at C-3 of the pyrrolone ring is produced during the reaction sequence. In the case of a 16-position of the imine moiety the yields are nearly quantitative but the diastereoselectivity is low whereas the sterical...The reaction of alpha,beta-unsaturated imines, derived from steroidal amines and cinnamaldehyde, with carbon monoxide and ethylene leads to the formation of steroids with a 1,3-dihydropyrrol-2-one ring system attached to the D-ring or the steroid. In addition, a new stereogenic center at C-3 of the pyrrolone ring is produced during the reaction sequence. In the case of a 16-position of the imine moiety the yields are nearly quantitative but the diastereoselectivity is low whereas the sterically more hindered 17-position shows a decreased reactivity but quite good diastereoselectivities. Complete diastereoselectivity is achieved if the starting compound exhibits an additional silyl ether group in the 17beta-position besides the imine subunit in the 16beta-position. The compound bearing the pyrrolone substituent at 17beta-position was characterized by means of X-ray crystallography showing that the rotation of the pyrrolone ring is hindered by a strong: intramolecular hydrogen bond between the carbonyl oxygen of the pyrrolone moiety and the hydrogen at C-17. The question of whether this intramolecular hydrogen bond is also responsible for the observed diastereoselectivities is discussed. » weiterlesen» einklappen

Autoren