Methyl 4-oxocyclohexanecarboxylate → Methyl 4-oxocyclohexanecarboxylate

Participants

Reaction Steps

The epoxides used as the starting materials in the general process described above can be obtained from available starting materials using an appropriate series of reactions. Thus, methyl 4-hydroxybenzoate is hydrogenated using 5% rhodium on alumina as catalyst to give methyl 4-hydroxycyclohexanecarboxylate. This is then oxidized with pyridinium chlorochromate resulting in methyl 4-oxocyclohexanecarboxylate. The 2-carbon homologation of methyl 4-oxocyclohexanecarboxylate to give methyl 4-(oxoethylidene)cyclohexanecarboxylate is carried out using the method developed by A. I. Meyers. Acetaldehyde t-butylimine is metalated with lithium diisopropylamide and then treated with diethyl chlorophosphate to provide the lithioeneaminephosphonate. Addition of methyl 4-oxocyclohexanecarboxylate and subsequent acid hydrolysis gives methyl 4-(oxoethylidene)cyclohexanecarboxylate. The reduction of this oxoethylidene compound with sodium borohydride gives methyl 4-(2-hydroxyethylidene)cyclohexanecarboxylate.

Provenance & Evidence