Diethyl chlorophosphate → Methyl 4-(2-oxoethylidene)cyclohexane-1-carboxylate
Reaction equation
C(N=CC)(C)(C)C.C([N-]C(C)C)(C)C.[Li+].P(Cl)(OCC)([O:18][CH2:19][CH3:20])=O.O=[C:26]1[CH2:31][CH2:30][CH:29]([C:32]([O:34][CH3:35])=[O:33])[CH2:28][CH2:27]1>>[O:18]=[CH:19][CH:20]=[C:26]1[CH2:31][CH2:30][CH:29]([C:32]([O:34][CH3:35])=[O:33])[CH2:28][CH2:27]1Participants
Procedure
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.
Workup
- customto provide the lithioeneaminephosphonate
Sources & evidence
- ORD record
- ord-03f4d275c25b414882dc8d9bdd405c13
- Source dataset
- uspto-grants-1988_05
- Patent number
- US04748274
Reaction notes
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