| 摘要 |
<p>Title cpds. are of formula (I): (where Y is H, OH or alkoxy; n is 1 or 0; R1 and R2 = H or straight or branched alkyl; X is O or 2H, but cannot be 2H when one of R1 and R2 is H, and the double bond indicated by the dotted lines is between 3a and 4 when R2 is alkyl; between 3a and 9b when R1 and R2 are both H and is in equilibrium between 3a and 9b, and 1 and 9b, when R2 is H and R1 is alkyl).</p> |
