Disconnection-reconnection

The vast majority of multistep syntheses involve either the disconnection, reconnection, or modification of what are loosely called appendages. One particularly useful retrosynthetic strategy consists of fragmenting a ring and then disconnecting the resulting appendages, as shown below. 

Most rearrangements well known to synthetic organic chemists as the Beckmann or Claisen rearrangement can be analyzed retrosynthetically as retro-rearrangements. They are characterized by multiple disconnections-reconnections. Detailed retrosynthetic consideration of some rearrangements is given in Chap. 8. 

This synthetic methodology was exploited to prepare (via a disconnection/reconnection... 

Figure 2.14 Use of a multistep disconnection/reconnection strategy for preparing tritium-labeled paclitaxel...

Figure 10.35 Application of the disconnection-reconnection strategy to the carbon-14 labeling of complex molecules [ C2]protoporphyrin IX dimethyl ester...

Figure 10.37 Use of the ozonolytic cleavage of C= C bonds in the disconnection-reconnection synthesis of (—)-a-[vinylidene- H2]-kainic acid...

Figure 10.41 Use of the 0s04-Nal04 cleavage of C C bonds in disconnection/reconnection syntheses of terminal olefins...

Both results (4) and (6) are in agreement with the expression of the disconnection-reconnection exponent. 

The value for Df depends on the type of disconnection-reconnection considered as shown in the beginning of this article. In addition, the case Df = D agrees perfectly with the Edwards et al. scaling for fragmentation of percolation clusters [12]. 

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