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4269720 
Journal Article 
Optimization of Manganese Coupling Reaction for Kilogram-Scale Preparation of Two Aryl-1,3-dione Building Blocks 
Smejkal, T; Gopalsamuthiram, V; Ghorai, SK; Jawalekar, AM; Pagar, D; Sawant, K; Subramanian, S; Dallimore, J; Willetts, N; Scutt, JN; Whalley, L; Hotson, M; Hogan, AM; Hodges, G 
2017 
1 
Organic Process Research and Development
ISSN: 1083-6160 
21 
10 
1625-1632 
WOS:000413709900020 
Aryl-l,3-diones represent a promising new class of herbicidal acetyl-CoA carboxylase (ACCase) inhibitors. The original synthesis of this structural motif employed in the research phase involved a selenium oxide mediated oxidation, the use of diazoacetate and aryl lead reagents, and a low temperature oxidation of an aryl lithium intermediate, so it was not well suited to large scale synthesis. For kilogram scale synthesis of the two aryl-1,3-dione building blocks (3 and 4), we developed an alternative route which employs a manganese or manganese-copper catalyzed alkyl Grignard coupling and a semi-pinacol rearrangement of an epoxide as the key steps. The optimized conditions could be of general interest, as scalable methods for the synthesis of 2-alkyl substituted benzaldehydes and of 2-aryl-1,3-diones.