Functional group retrosynthetic changes

Second, we need to determine whether there is a change in the identity or location of the functional group. In this case, the functional group has changed both its identity and its location. The functional group in the product is an aldehyde moiety. As seen in Section 10.7, an aldehyde can be made via hydroboration-oxidation of an alkyne. As shown with the retrosynthetic arrow, a terminal alkyne can be converted into an aldehyde. 

Remember that it helps to use retrosynthetic analysis in synthesis problems. This means working backward to simpler and simpler compounds until an available compound is reached. These problems offer an additional clue in that the starting material is specified. In such cases it is often useful to identify which carbons in the target come from the carbons of the starting material. It is usually advisable to change these carbons as little as possible. It is also useful to identify which carbon-carbon bonds must be formed in the synthesis and how any functional groups need to be modified. In some cases the entire path will be apparent after this examination. In others it will be neces-... 

Retrosynthetic analysis involves the disassembly of a TM into available starting materials by sequential disconnections and functional group interconversions. Structural changes in the retrosynthetic direction should lead to substrates that are more readily available than the TM. Synthons are fragments resulting from disconnection of carbon-carbon bonds of the TM. The actual substrates used for the forward synthesis are the synthetic equivalents (SE). Also, reagents derived from inverting the polarity (IP) of synthons may serve as SEs. 

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