Disconnection of Dialkyl Ketones

In the introductory example (Sect. 1.3.1) we considered disconnection of TM la by refra-Friedel-Crafts and rctro-Grignard. Both reactions are useful in the synthesis of aryl alkyl ketones of diverse complexity. In dialkyl ketones we consider the carbonyl group as directing the preferred C-C bond disconnection. 

Example 2.10 Propose the retrosynthetic analysis for TM 2.10 and suggest possible reagents. 

P-Keto acid TM 2.10d is not available therefore, the synthetic route according to disconnection a is preferred. The reader should propose a synthetic route to TM 2.10 considering the most effective approach to TM 2.10a. 

Example 2.11 Complete the retrosynthesis and propose the synthesis of benzyl acetone TM 2.11. 

The key step represents elimination of CO2 in the concerted process mnning over the six-memhered transition state and is therefore energetically favorable. Easy and selective alkylation of the methylenic group in ethyl acetoacetate, the simple decarboxylation in the last steps and availability of this starting material make it the reagent of choice for acetonide carbanion. Ethyl acetoacetate is a commodity produced by the catalytic process discussed in connection with the retrosynthetic analysis of TM 2.13. 

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