A comparison of (chloromethyl)- and (iodomethyl)zinc cyclopropanation reagents
摘要:
A study comparing the rate of cyclopropanation of a range of olefins using (chloromethyl)- and (iodomethyl)zinc reagents is described. The (chloromethyl)zinc reagent derived from diethylzinc and chloroiodomethane is generally more reactive than the (iodomethyl)zinc analogue. The use of 1,2-dichloroethane as the solvent for these reactions was shown to be a crucial factor necessary to achieve clean, rapid, high-yielding cyclopropanations. The well-known directing effect of proximal oxygen substituents on the stereochemical outcome of "Simmons-Smith" cyclopropanations was shown to hold for the (chloromethyl)zinc reagent as well. The diethylzinc/chloroiodomethane reagent system in 1,2-dichloroethane should prove to be a valuable alternative to traditional (iodomethyl)zinc-based cyclopropanation reagents.
A comparison of (chloromethyl)- and (iodomethyl)zinc cyclopropanation reagents
作者:Scott E. Denmark、James P. Edwards
DOI:10.1021/jo00025a007
日期:1991.12
A study comparing the rate of cyclopropanation of a range of olefins using (chloromethyl)- and (iodomethyl)zinc reagents is described. The (chloromethyl)zinc reagent derived from diethylzinc and chloroiodomethane is generally more reactive than the (iodomethyl)zinc analogue. The use of 1,2-dichloroethane as the solvent for these reactions was shown to be a crucial factor necessary to achieve clean, rapid, high-yielding cyclopropanations. The well-known directing effect of proximal oxygen substituents on the stereochemical outcome of "Simmons-Smith" cyclopropanations was shown to hold for the (chloromethyl)zinc reagent as well. The diethylzinc/chloroiodomethane reagent system in 1,2-dichloroethane should prove to be a valuable alternative to traditional (iodomethyl)zinc-based cyclopropanation reagents.
The chromium trioxide–3,5-dimethylpyrazole complex: a mild and selective reagent for the oxidation of cyclopropyl hydrocarbons
作者:Martin G. Banwell、Najiba Haddad、Julie A. Huglin、Maureen F. MacKay、Monica E. Reum、John H. Ryan、Kathleen A. Turner (née Herbert)
DOI:10.1039/c39930000954
日期:——
The title complex selectively oxidises the methylene unit adjacent to a cyclopropane ring producing synthetically useful yields of the corresponding cyclopropyl ketones and/or products resulting from cleavage of the three-membered ring.