Task 1: 2,3-disubstituted cyclopentanones with vinyl groups at C-3 should be prepared via an asymmetric Tandem 1,4-addition/ Dieckmann cyclization. Task 2: The diastereoselectivity of the Claisen rearrangement of chiral propargyl enol ethers towards 2,2,3-trisubstituted cyclopentanones should be investigated.
Task 3: The proposed synthesis of 7a-substituted steroids should follow the D-> ABCD approach which has not been accomplished yet. The ring D building block has to be connected with an alkyne side chain forming an enediyne. A diastereoselective cobaltmediated cyclization of this enediyne should afford the steroidal skeleton with 7a-configuration. This steroid should be converted into biologically active steroids with antitumor activities.
Task 4: Starting from a key intermediate which allows the introduction of unnatural substituents at C-7 on a very late step of the synthesis a variety of 7a-substituted steroids should be prepared. The pharmacological properties of these new unnatural steroids should be investigated.