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Intermolecular Cyclopropanation (intermolecular + cyclopropanation)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Gold(I)-Catalyzed Intermolecular Cyclopropanation of Enynes with Alkenes: Trapping of Two Different Gold Carbenes.

CHEMINFORM, Issue 52 2006
Salome Lopez
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

First Intermolecular Cyclopropanation of Fischer Dialkylaminocarbene Complexes.

CHEMINFORM, Issue 15 2003
Synthesis of 1-Aminocyclopropanecarboxylic Acid Derivatives.
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Rhodium(II)-Catalyzed Inter- and Intramolecular Cyclopropanations with Diazo Compounds and Phenyliodonium Ylides: Synthesis and Chiral Analysis

HELVETICA CHIMICA ACTA, Issue 2 2005
Ashraf Ghanem
Different classes of cyclopropanes derived from Meldrum's acid (=2,2-dimethyl-1,3-dioxane-4,6-dione; 4), dimethyl malonate (5), 2-diazo-3-(silyloxy)but-3-enoate 16, 2-diazo-3,3,3-trifluoropropanoate 18, diazo(triethylsilyl)acetate 24a, and diazo(dimethylphenylsilyl)acetate 24b were prepared via dirhodium(II)-catalyzed intermolecular cyclopropanation of a set of olefins 3 (Schemes,1 and 4,6). The reactions proceeded with either diazo-free phenyliodonium ylides or diazo compounds affording the desired cyclopropane derivatives in either racemic or enantiomer-enriched forms. The intramolecular cyclopropanation of allyl diazo(triethylsilyl)acetates 28, 30, and 33 were carried out in the presence of the chiral dirhodium(II) catalyst [Rh2{(S)-nttl)4}] (9) in toluene to afford the corresponding cyclopropane derivatives 29, 31 and 34 with up to 37% ee (Scheme,7). An efficient enantioselective chiral separation method based on enantioselective GC and HPLC was developed. The method provides information about the chemical yields of the cyclopropane derivatives, enantioselectivity, substrate specifity, and catalytic activity of the chiral catalysts used in the inter- and intramolecular cyclopropanation reactions and avoids time-consuming workup procedures. [source]

Unprecedented Stereoselective Synthesis of Catalytically Active Chiral Mo3CuS4 Clusters

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2006
Marta Feliz Dr.
Abstract Cluster excision of polymeric {Mo3S7Cl4}n phases with chiral phosphane (+)-1,2-bis[(2R,5R)-2,5-(dimethylphospholan-1-yl)]ethane ((R,R)-Me-BPE) or with its enantiomer ((S,S)-Me-BPE) yields the stereoselective formation of the trinuclear cluster complexes [Mo3S4{(R,R)-Me-BPE}3Cl3]+ ([(P)- 1]+) and [Mo3S4{(S,S)-Me-BPE}3Cl3]+ ([(M)- 1]+), respectively. These complexes posses an incomplete cuboidal structure with the metal atoms defining an equilateral triangle and one capping and three bridging sulfur atoms. The P and M symbols refer to the rotation of the chlorine atoms around the C3 axis, with the capping sulphur atom pointing towards the viewer. Incorporation of copper into these trinuclear complexes affords heterodimetallic cubane-type compounds of formula [Mo3CuS4{(R,R)-Me-BPE}3Cl4]+ ([(P)- 2]+) or [Mo3CuS4{(S,S)-Me-BPE}3Cl4]+ ([(M)- 2]+), respectively, for which the chirality of the trinuclear precursor is preserved in the final product. Cationic complexes [(P)- 1]+, [(M)- 1]+, [(P)- 2]+, and [(M)- 2]+ combine the chirality of the metal cluster framework with that of the optically active diphosphane ligands. The known racemic [Mo3CuS4(dmpe)3Cl4]+ cluster (dmpe=1,2-bis(dimethylphosphanyl)ethane) as well as the new enantiomerically pure Mo3CuS4 [(P)- 2]+ and [(M)- 2]+ complexes are efficient catalysts for the intramolecular cyclopropanation of 1-diazo-5-hexen-2-one (3) and for the intermolecular cyclopropanation of alkenes, such as styrene and 2-phenylpropene, with ethyl diazoacetate. In all cases, the cyclopropanation products were obtained in high yields. The diastereoselectivity in the intermolecular cyclopropanation of the alkenes and the enantioselectivity in the inter- or intramolecular processes are only moderate. La reacción de escisión de la fase polimérica {Mo3S7Cl4}ncon la fosfina quiral (+)-1,2-bis[(2R,5R)-2,5-(dimetilfosfolan-1-il)]etano, (R,R)-Me-BPE, o con su enantiómero, (S,S)-Me-BPE, conduce a la formación estereoselectiva de los complejos clúster trinucleares [Mo3S4(R,R -Me-BPE)3Cl3]+([(P)- 1]+) y [Mo3S4(S,S -Me-BPE)3Cl3]+([(M)- 1]+), respectivamente. Estos complejos poseen una estructura de cubo incompleto, dónde los átomos metálicos definen un triángulo equilátero, con un azufre unido a tres átomos de molibdeno y tres azufres puente. Los símbolos P y M hacen referencia a la rotación de los átomos de cloro alrededor del eje C3, con el azufre apuntado dirigido hacia el observador. La incorporación de cobre a estos complejos trinucleares conduce a compuestos heterodimetálicos con estructura tipo cubano de fórmula [Mo3CuS4(R,R -Me-BPE)3Cl4]+([(P)- 2]+) y [Mo3CuS4(S,S -Me-BPE)3Cl4]+([(M)- 2]+) donde la quiralidad del precursor trinuclear se mantiene en el producto final. Los complejos catiónicos [(P)- 1]+, [(M)- 1]+, [(P)- 2]+y [(M)- 2]+combinan la quiralidad del esqueleto clúster con la de los ligandos difosfina. El clúster racémico [Mo3CuS4(dmpe)3Cl4]+(dmpe=1,2-bis(dimetilfosfino)etano), así como los complejos Mo3CuS4 enantioméricamente puros [(P)- 2]+o [(M)- 2]+son catalizadores eficaces para la reacción de ciclopropanación intramolecular de 1-diazo-5-hexen-2-ona (3) y para la ciclopropanación intermolecular de alquenos, estireno y 2-fenilpropeno, con etil diazoacetato. En todos los casos los productos de ciclopropanación se obtienen con rendimientos elevados. La diastereoselectividad en la ciclopropanación intermolecular de alquenos y la enantioselectividad en los procesos tanto inter- como intramoleculares son únicamente moderadas. [source]