35225-24-2Relevant academic research and scientific papers
A practical approach to stereodefined cyclopropyl-substituted heteroarenes using a Suzuki-type reaction
Yao, Min-Liang,Deng, Min-Zhi
, p. 425 - 428 (2007/10/03)
In the presence of Pd(PPh3)4, NaBr and KF · 2H2O the cross-coupling reaction of heteroaryl triflates with trans-cyclopropylboronic acids proceeds readily to give pure trans-cyclopropyl heteroarenes in moderate to good yields. The X-ray crystallography of compound 3g and 1H-NMR spectra of all products show that the configuration of the cyclopropyl group was retained during the reaction. Under the same reaction conditions, highly optically active cyclopropyl-substituted heteroarenes (up to 94% ee) were obtained by cross-coupling of heteroaryl/triflates with enantiomerically enriched cyclopropylboronic acids.
Palladium-catalyzed cross-coupling reaction of cyclopropylboronic acids with aryl triflates
Yao, Min-Liang,Deng, Min-Zhi
, p. 1095 - 1100 (2007/10/03)
In the presence of appropriate base and NaBr, the Suzuki- type reaction of aryl triflates and trans-cyclopropylboronic acids proceed readily to give pure trans-cyclopropylarenes in good to high yields. For the reaction of general aryl triflates, the base KF·2H2O is efficient, but in the case of aryl triflates bearing electron donating groups, KF·2H2O as a base makes the unexpected phenylaryl exchange between the phenyl of Pd(PPh3)4 and the aryl of triflate to occur. The use of K3PO4·3H2O instead of KF·2H2O can inhibit the unexpected phenyl-aryl exchange, but the yield of the product is somewhat decreased. The coupling reaction of aryl triflates with the optically active cyclopropylboronic acids, which were easily obtained in good yield and with good to excellent ee (up to 94%) by the asymmetric cyclopropanation of alkenylboronates with optically pure TMTA auxiliary, was also investigated. During the coupling reaction, the absolute configuration of the cyclopropyl group was retained. Thus, a novel method to prepare aryl- substituted cyclopropanes, including highly optically active cyclopropanes, from phenols or arylamines was provided.
Kinetic Study of the Homolytic Brominolysis of 1,2-Diarylcyclopropanes
Applequist, Douglas E.,Gdanski, Rick D.
, p. 2502 - 2510 (2007/10/02)
The rate constants for the photolytic brominolysis of 22 trans-1,2-diarylcyclopropanes in carbon disulfide relative to an internal standard, p-chlorotoluene, have been determined.The products of the brominolysis are 1,3-dibromo-1,3-diarylpropanes.The rate constants range over 5 orders of magnitude, being enhanced by electrondonating substituents on one or both benzene rings.The quantitative size of the substituent effect (ρ) at either involved carbon center is a function of the substituent at the other center.This fact suggests a continuum of transition-state structures with varying degrees of bond breaking and charge separation.
