The direct preparation of functionalised cyclopropanes from allylic alcohols or α-hydroxyketones using tandem oxidation processes
作者:Graeme D. McAllister、Magalie F. Oswald、Richard J. Paxton、Steven A. Raw、Richard J.K. Taylor
DOI:10.1016/j.tet.2005.12.078
日期:2006.7
carried out in the presence of a stabilised sulfurane, and the intermediate α,β-unsaturated carbonyl compound undergoes in situ cyclopropanation. By using a combination of stabilisedphosphorane and sulfurane, the direct conversion of allylic alcohols or α-hydroxyketones into functionalised cyclopropanes is achieved, with in situ cyclopropanation being followed by Wittig olefination, or vice versa. The
Catalytic cyclopropanation of electron deficient alkenes mediated by chiral and achiral sulfides: scope and limitations in reactions involving phenyldiazomethane and ethyl diazoacetate
作者:Varinder K. Aggarwal、Helen W. Smith、George Hynd、Ray V. H. Jones、Robin Fieldhouse、Sharon E. Spey
DOI:10.1039/b004367m
日期:——
Phenyldiazomethane reacts with electron deficient alkenes in the presence of catalytic amounts of transition metal catalyst [Rh2(OAc)4 was better than Cu(acac)2] and catalytic amounts of sulfide to give cyclopropanes. Pentamethylene sulfide was found to be superior to tetrahydrothiophene and the optimum solvent was toluene. Under these optimised conditions a range of enones were cyclopropanated in
The Formation of Cyclopropane Derivatives Bearing 1,2-Dicarbonyl Groups through Tandem Michael-Favorskii-Type Reactions with(E)-?-Styrylselenonium Triflate
A novel tandemMichael–Favorskii-typereaction is described. Treatment of active methylene carbanions, prepared by the reaction of NaH and active methylene compounds, with (E)-β-styrylselenonium triflate in DMF at 70 °C for 3 h gave cyclopropanederivativesbearing1,2-dicarbonylgroups in moderate to good yields. On the other hand, the carbanions derived from malonates reacted with the selenonium
Ethyl diazoacetate adds to 1,3-diarylpropenones in a regioselective fashion to give intermediate 4,5-dihydro-3H-pyrazole derivative; 1,3-hydride shift in the latter leads to formation of isomeric ethyl 4-aryl-5-aroyl-4,5-dihydro-1H-pyrazole-3-carboxylate and ethyl 4-aryl-3-aroyl-4,5-dihydro-1H-pyrazole-5-carboxylate at a ratio of 5:1. Thermolysis of these products is not stereospecific; as a result, three isomeric substituted ethyl cyclopropanecarboxylates and 2-pyranone derivative are formed.
Hantawong, Kesra; Murphy, William S., Journal of Chemical Research, Miniprint, 1988, # 10, p. 2520 - 2547