Tetrahydro-6-methyl-2-pyranone

Using your roadmaps as a guide, show how to convert 5-chloro-2-pentanone and carbon dioxide into racemic tetrahydro-6-methyl-2-pyranone.You must use 5-chloro-2-pentanone and carbon dioxide as the source of all carbon atoms in the racemic target... 

The Reformatsky reaction has been applied to the synthesis of fused pyranones and provides an example of selective isomer formation by careful choice of substrate. Hydroxy-methylenecyclohexanone (315) and methyl bromoacetate give 5,6,7,8-tetrahydro-l-benzopyran-2-one (316) through alkylation at the hydroxymethylene carbon atom (54JA6388). However, the benzoyl derivative (317) is unable to form an enolate salt and alkylation occurs at the carbonyl carbon atom, leading to 5,6,7,8-tetrahydro-2-benzopyran-3-one (318) (45HCA771). 

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