A new synthetic method of conjugated enones by the use of carbanion-induced Favorskii-typerearrangement is described. The reaction of α,α′-dihalo ketones R1R2(X)CC(O)CH2X with sodiomalonates Na+ −CR3(CO2R4)2 in THF at 0°C—room temperature gave conjugated enones R1R2C=CHC(O)CR3(CO2R4)2 in 42–66% yields. The reaction can be also adaptable to the enolates of ethyl cyanoacetate or malononitrile to give
1,1-Dichloro- and 1,3-dichloro-2-alkanones react with 2-methylfuran in the presence of lithium perchlorate/triethylamine to form 2-chloro-1-methyl-8-oxabicyclo [3.2.1]oct-6-ene-3-ones predominantly.
The favorskii rearrangement of dichlorinated methylketones
作者:N. Schamp、N. De Kimpe、W. Coppens
DOI:10.1016/0040-4020(75)80198-0
日期:1975.1
Twenty-two dichlorinated methylketones have been submitted to Favorskiirearrangement in NaOMeMeOH. Distribution of products is strongly dependent on substitution. Primary dichloromethyl-ketones (R2 = H) gave rise to Favorskii esters only. Results are explained by a cyclopropanone intermediate, which is formed stereospecifically by disrotative closure of a delocalized zwitter-ion. Opening of the cyclopropanone
Reaction of 1,3-dihalo-3-methy]-2-butanone with t-butyl acetoacetate (NaH) gave t-butyl 3,4-dihydro-2,2,6-trimethyl-4-oxo-2H-pyran-5-carboxylate via the Favorskii-type rearrangement. Michael addition of 4-methylphenyllithium (CuI) followed by ring cleavage with Me3 SiCl-NaI in DMF or PrCN afforded ar-atlantone as well as (±)-ar-turmerone selectively.
1,3-二卤-3-甲基] -2-丁酮与乙酰乙酸叔丁酯(NaH)反应生成叔丁基3,4-二氢-2,2,6-三甲基-4-氧代-2H-吡喃-通过Favorskii型重排生成5-羧酸盐。迈克尔加成4- methylphenyllithium(CUI)的随后用我环切割3在DMF或PRCN得到的SiCl-的NaI AR -atlantone以及(±) -芳-turmerone选择性。
FOEHLISCH, B.;FLOGAUS, R.;OEXLE, J.;SCHAEDEL, A., TETRAHEDRON LETT., 1984, 25, N 17, 1773-1776
作者:FOEHLISCH, B.、FLOGAUS, R.、OEXLE, J.、SCHAEDEL, A.