Study On Synthesis Of Ionyl Esters Flavor Precursor

The paper reviewed the research and development of tobacco flavor precursor, iononeskeleton flavor precursors and allylic oxidation.With α-and β-ionone as the raw material,synthesis ionone skeleton of precursor of3-oxo-α-ionyl acetate,3-oxo-α-ionyl ethyl oxalate,3-oxo-α-ionol ethyl carbonate,4-oxo-β-ionol acetate,4-oxo-β-ionyl ethyl oxalate,4-oxo-β-ionol ethyl carbonate, α-ionyl acetate, α-ionyl ethyl oxalate, α-ionyl ethyl carbonate, β-ionylacetate. The reactions β-ionol with ethyl oxalyl chloride and ethyl chloride have been studied,Both get5,7,9-megastigmatrlene.Synthesis of α-and β-ionol by optimization reduction with NaBH4and CaCl2.α-and β-ionolwere esterified to form non-volatile flavor precursors—α-ionyl acetate, β-ionol acetate, α-ionylethyl oxalate, α-ionol ethyl carbonate by acetic anhydride, ethyl oxalyl chloride, ethyl chloride.The paper discussed the formation mechanism of the main product during the process of synthe-sis of β-ionyl ethyl oxalate, β-ionol ethyl carbonate.Using tert-butyl hydrogen peroxide andsodium hypochlorite as the oxidant, α-ionone and β-ionone are used as raw materials by allylicoxidation to get the corresponding oxo-ionones, we get the optimal reaction condition: ratio ofn(ionone): n(TBHP):n(NaClO) is1:8:3, reaction temperature0~5℃and reaction time4hrs.The yield of3-oxo-α-ionone is50.9%. And4-oxo-β-ionone is58.1%. We get oxo-ionols byselective reduction with NaBH4and CaCl2. The optimal reaction condition: ratio of n(ionone):n(NaBH4): n(CaCl2) is1.0:0.30:2.5, reaction temperature0~5℃and reaction time0.5h, Theyield of3-oxo-α-ionol is91.9%. And4-oxo-β-ionol is83.1%.With acetic anhydride, ethyloxalyl chloride, ethyl chloride as esterification reagent, we get the corresponding tobacco flavorprecursors. Optimal the esterification yields of3-oxo-α-ionyl acetate,3-oxo-α-ionyl ethyloxalate,3-oxo-α-ionol ethyl carbonate were69%,79.2%and64.5%. All structures ofintermediates and products were confirmed by IR、1HNMR、13CNMR and MS.