Illogical Disconnections with Participation of Two Groups

Abstract Compounds with a 1,2-, 1,4- and 1,6-dioxygen pattern and related bifunctional structures are presented. Disconnection of the internal bonds results in illogical synthons because of the mismatch of charges in the patterns with an even number of C atoms between the functional groups. Three-membered heterocyclic rings are presented as an important class of illogical nucleophiles in the retrosyn-thesis of the 1,2-difunctional pattern. Retrosynthesis of the 1,6-dicarbonyl pattern by reconnection and rctro-Birch reduction of the aromatic building block is related to chemoselective Birch reduction and ozonolysis in the synthetic route. The retrosynthesis and synthesis of salbutamol and asymmetric synthesis of —)-frontalin are presented. 

Here the specific retroanalysis for the 1,6-CO pattern is not presented, which is discussed in Sect. 5.4. 

Destabilized synthons with charges opposite to the natural polarization of the bond often have acceptable though not easily recognizable reagents or synthetic equivalents. After all, syntheses of numerous compounds with even distances of functional groups are successfully completed by formation of C-C bonds. They are important intermediates in the syntheses of complex natural compounds. In the next sections, we discuss the retrosynthetic approach to such compounds. 

Sunjic and V. Petrovic Perokovic, Organic Chemistry from Retrosynthesis to Asymmetric Synthesis, DOI 10.1007/978-3-319-29926-6 5 

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