| 摘要 |
Methods are provided for preparing a compound with a fused ring structure of formula (XIV) which comprises one or more reactions starting from a 21-cyano compound of formula (XVI) where typically; R1 is an amidomethylene group or an acyloxymethylene group; R5 and R8 are independently chosen from -H, -OH or -OCOCH2OH, or R5 and R8 are both keto and the ring A is a p-benzoquinone ring; R14a and R14b are both -H ozone is -H and the other is -OH, -OCH3 or -OCH2CH3, or R14a and R14b together form a keto group; and R15 and R18 are independently chosen from -H or -OH, or R5 and R8 are both keto and the ring A is a p-benzoquinone ring. In modified starting materials, the 21-cyano group can be replaced by other groups introduced using nucleophilic reagents.
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