Synthesis of optically active 5-alkoxy-6-methylcyclohex-2-en-1-ones and 4-alkoxy-5-methylcyclopent-1-enyl benzoate.
The reaction of (-)-(1E,3Z)-2-methyl-1-((1S)-1-phenylethoxy)penta-1,3-dien-3-ol benzoate with allyltrimethylsilane in SO2 and in the presence of a catalytic amount of Tf2NTMS gives a silyl sulfinate intermediate that furnishes (-)-(6Z,1'S,4S,5S)-5-methyl-4-(1'-phenylethoxy)octa-1,6-dien-6-yl benzoate after acidic workup. The latter undergoes ring-closing metathesis producing (-)-(2S,3S)-2-methyl-3-((1S)-1-phenylethoxy)cyclopent-5-en-1-yl benzoate. It has been converted also into the corresponding trimethylsilyl enol ether. After oxidation, an enone is obtained that undergoes ring-closing metathesis giving (-)-(5S,6S)-6-methyl-5-((1S)-1-phenylethoxy)cyclohex-2-en-1-one.
Turks
Maris
M
Laboratory of Glycochemistry and Asymmetric Synthesis, Swiss Federal Institute of Technology (EPFL), Batochime, CH-1015 Lausanne, Switzerland.
Vogel
Pierre
P
D001565:Benzoates / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D003510:Cyclohexanes / Q000138:chemical synthesis* / Q000737:chemistry; D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D013237:Stereoisomerism
C534899:(2S,3S)-2-methyl-3-((1S)-1-phenylethoxy)cyclopent-5-en-1-yl benzoate; D001565:Benzoates; D003510:Cyclohexanes; D003517:Cyclopentanes