Acyclic Strategic Disconnections

The most useful general criteria for the assessment of acyclic strategic disconnections are summarized below. Most of these are based on the retrosynthetic preservation of building blocks and expeditious reduction of molecular size and complexity. 

arylalkyl, aryl, and other building-block type groups should not be internally disconnected (preserved bonds). 

A disconnection which produces two identical structures or two structures of approximately the same size and structural complexity is of high merit. Such disconnections may involve single or multiple bonds. 

Bonds between carbon and various heteroatoms (e.g. O, N, S, P) which are easily generated synthetically are strategic for disconnection. Specific bonds in this category are ester, amide, imine, thioether, and acetal. 

The dissection of skeletally embedded cyclic systems (i.e. rings within chains) into molecular segments is frequently best accomplished by acyclic bond disconnection, especially when such rings are separated by one or more chain members. Such acyclic bonds may be attached directly (i.e. exo) to a ring, or 1, 2, or 3 bonds removed from it, depending on the type of ring which is involved. 

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