Strategic bonds, cyclic

There are usually certain bonds in a molecule whose disconnection in the retrosynthetic direction leads to a significant simplification of the cyclic structure. These are termed strategic bonds. Since these have been described in detail elsewhere, we shall consider them here only briefly. ... 

Rule 6 None of the bonds which are part of a cyclic system linking a pair of common atoms (i.e., fused, bridgedheads or spiro-hng junction atoms) may be considered to be "strategic" if this cyclic system contains chiral centres. In this way retrosynthetic cleavages which would leave chiral centres on side chains are avoided... 

There are several ways to control the location of the double bond in the cyclic product by employing heteroatoms at strategic sites in the acyclic substrate. For example,... 

---