Design Through Disjunction

Disjunction comes in where there is the systematic formulation of analogues of a prototype agent, in general, toward structurally simpler products, which may be viewed as partial or quasi-replicas of the prototype agent. 

The method of disjunction is usually employed in three different meamers, namely  

From the above the following three observations may be made. They inelude  

however, pertinent to mention here that in the following three different possible structures of diethylstilbesterol analogues, the oestrogenic potency decreases substantially as the distance Zl between the two hydroxyl groups decreases. 

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The first synthetic oestrogen traws-diethylstilbesterol came into existence by applying the principle of drug-design through disjunction Ifom oestradioE. Explain. 

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