Approaches to the assembly of the antifungal agent FR-900848: studies on the asymmetric synthesis of bicyclopropanes and an X-ray crystallographic analysis of (4R,5R)-2-[(1R,3S,4S,6R)-6-phenyl-1-bicyclopropyl]-1,3-dimethyl-4,5-diphenylimidazolidine
Approaches to the assembly of the antifungal agent FR-900848: studies on the asymmetric synthesis of bicyclopropanes and an X-ray crystallographic analysis of (4R,5R)-2-[(1R,3S,4S,6R)-6-phenyl-1-bicyclopropyl]-1,3-dimethyl-4,5-diphenylimidazolidine
AsymmetricSimmons-Smithreactions of α,β-unsaturated acetals derived from chiral dialkyl tartrate or (2R,4R)-2,4-pentanediol are described. Treatment of the acetal with diethylzinc and methylene iodide gives a cyclopropane with high diastereoselectivity. The acetal group is readily transformed to the aldehyde or the ester group. In addition, the method is successfully applied to the enantioselective
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.
An asymmetric Simmons-Smith reaction
作者:Isao Arai、Atsunori Mori、Hisashi Yamamoto
DOI:10.1021/ja00312a072
日期:1985.12
ARAI, ISAO;MORI, ATSUNORI;YAMAMOTO, HISASHI, J. AMER. CHEM. SOC., 1985, 107, N 26, 8254-8256
作者:ARAI, ISAO、MORI, ATSUNORI、YAMAMOTO, HISASHI
DOI:——
日期:——
MORI ATSUNORI; ARAI ISAO; YAMAMOTO HISASHI; NAKAI HISAO; ARAI YOSHINOBU, TETRAHEDRON, 42,(1986) N 23, 6447-6458