Synthesis of 5,5,10,10‐tetramethyl‐1‐oxacyclotridecane‐6,7,8,9‐tetrone – on the mechanism of the Rubottom reaction

The synthesis of 5,5,10,10‐tetramethyl‐1‐oxacyclotridecan‐6,7,8,9‐tetrone ( 12 ) was achieved via a multistep procedure involving an oxidation known as the Rubottom reaction. The key intermediates were the dialdehyde ( 25 ), the diacid ( 33 ), the cyclic diketone ( 39 ) and the bis(silyl enol ether) ( 42 ). The oxidation of 42 with m CPBA yielded two diastereomers, the syn and anti bis(α‐hydroxy ketones) ( 44, 45 ) the ratio of which depends strongly on the solvent used. This result combined with the isolation of the diepoxide ( 43 ) gives an insight into the stereochemistry of the Rubottom reaction.