ConclusionThe oxymercuration-demercuration of olefins has previously been shown to be a highly convenient synthetic method for the Markovnikov hydration of olefins. The present paper has demonstrated a wide range of reactivity accompanying variation of olefin structure. Accordingly, considerable selectivity in the monooxymercuration of dienes is expected. Steric
The kinetic data are listed in Tables III-VII.Acknowledgment. We are grateful to Miss Takako Ishibashi for helpful discussions and experimental assistance.
The preparation of ethyl
4-ethoxy-2-methylcyclohexa-1,3-diene-1-carboxyate, ethyl 4-isopropoxy-
2-methylcyclohexa-1,3-diene-1-carboxylate, t-butyl
4-isopropoxy-2-methylcyclohexa-1,3-diene-1- carboxylate, ethyl 4-(t-butylcarbonyloxy)-2-methylcyclohexa-1,3-diene-1-carboxylate,
and t-butyI 4-(t-butylcarbonyloxy)-2-methylcyclohexa-1,3-diene-1-carboxylate
from Hagemann's ester and its t-butyl analogue in the presence of diethyl or diisopropyl sulfates and sodium hydride in dimethyl
sulfoxide, or pivaloyl chloride and N,N,N',N'-tetramethylethylenediamine
in tetrahydrofuran is described. The foregoing dienol ethers and esters are
smoothly deprotonated by lithium diisopropyl-
amide in tetrahydrofuran at -78" to give the corresponding ester dienolates, which react regio- specifically with a number
of electrophiles, either a or y to the alkoxycarbonyl group of the dienol ether or ester. A number
of the products, which are generally obtained in good yields, have been hydrolysed to Hagemann's ester derivatives substituted
exclusively at C1.
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