36617-02-4Relevant articles and documents
Metal catalyzed carbonylation of gem-dibromocyclopropanes
Grushin,Alper
, p. 3349 - 3352 (1991)
The first examples of the catalytic carbonylation of gem-dibromocyclopropanes is described, using cobalt and nickel salts as catalysts under phase transfer conditions.
Stereoselective Functionalization of Racemic Cyclopropylzinc Reagents via Enantiodivergent Relay Coupling
An, Lun,Tong, Fei-Fei,Zhang, Shu,Zhang, Xingang
supporting information, p. 11884 - 11892 (2020/08/06)
Efficient construction of optically pure molecules from readily available starting materials in a simple manner is an ongoing goal in asymmetric synthesis. As a straightforward route, transition-metal-catalyzed enantioconvergent coupling between widely available secondary alkyl electrophiles and organometallic nucleophiles has emerged as a powerful strategy to construct chiral center(s). However, the scope of racemic secondary alkylmetallic nucleophiles for this coupling remains limited in specific substrates because of the difficulties in stereoselective formation of the key alkylmetal intermediates. Here, we report an enantiodivergent strategy to efficiently achieve an array of synthetically useful chiral cyclopropanes, including chiral fluoroalkylated cyclopropanes and enantiomerically enriched cyclopropanes with chiral side chains, from racemic cyclopropylzinc reagents. This strategy relies on a one-pot, two-step enantiodivergent relay coupling process of the racemic cis-cyclopropylzinc reagents with two different electrophiles, which involves kinetic resolution of racemic cis-cyclopropylzinc reagents through a nickel-catalyzed enantioselective coupling with alkyl electrophiles, followed by a stereospecific relay coupling of the remaining enantiomeric cyclopropylzinc reagent with various electrophiles, to produce two types of functionalized chiral cyclopropanes with opposite configurations on the cyclopropane ring. These chiral cyclopropanes are versatile synthons for diverse transformations, rendering this strategy effective for obtaining structurally diversified molecules of medicinal interest.
Preparation of arylspiro[2.4]hept-5-enes from aryldibromocyclopropanes via diallylation and metathesis reaction
Lin, Shaw-Tao,Lee, Chuan-Chen,Hu, Cheng-Kwan
, p. 591 - 592 (2007/10/03)
A series of arylspiro[2.4]hept-5-enes can be prepared from aryl-diallylcyclopropanes by using Grubbs' catalyst in good yields.
Hydrodehalogenation of 1,1-dibromocyclopropanes by Grignard reagents promoted by titanium compounds
Dulayymi, Juma'a R. Al,Baird, Mark S.,Bolesov, Ivan G.,Nizovtsev, Alexey V.,Tverezovsky, Viacheslav V.
, p. 1603 - 1618 (2007/10/03)
1,1-Dibromocyclopropanes are converted into the corresponding monobromocyclopropanes (as mixtures of stereoisomers where appropriate) by reaction with 1.0-1.3 mol equiv. of ethylmagnesium bromide and 2-10 mol% titanium isopropoxide for 90%). With ethylmagnesium bromide, the reaction occurs very slowly in the absence of catalyst; with methylmagnesium bromide, the reaction does occur in the absence of catalyst, but is only slightly promoted in the presence of titanium isopropoxide. Reactions with a number of other Grignard reagents are also discussed. In the case of phenethylmagnesium bromide, the major product containing the phenethyl-group is ethylbenzene, together with small amounts of styrene and ethyl 4-phenyl-2-butyl ether, a product of trapping of the solvent, ether. In other cases, relatively large amounts of a diether, formally derived by hydrogen ion adjacent to the ether oxygen followed by dimerisation, are isolated. No products were identified incorporating the cyclopropane and either the Grignard alkyl group or the solvent. Labelling studies indicate that the hydrogen introduced into the cyclopropane is not derived from either the α- or β-positions of the Grignard reagent. When the reduction is carried out with phenethylmagnesium bromide in d8-tetrahydrofuran both monobromides contain deuterium.
