105367-38-2

Upstream product

• 100-42-5 styrene 
• 63254-50-2 L-menthyl diazoacetate 
• 65437-23-2 d-menthyl diazoacetate 

Relevant academic research and scientific papers

Preparation and application of bisoxazoline ligands with a chiral spirobiindane skeleton for asymmetric cyclopropanation and allylic oxidation

A new type of bisoxazoline ligand 4 (abbreviated as SpiroBOX) containing a chiral spirobiindane scaffold were easily prepared in high yields from enantiomerically pure 1,1′-spirobiindane-7,7′-diol (SPINOL) with 1,1′-spirobiindane-7,7′-dicarboxylic acid as

Bisoxazoline ligands with an axial-unfixed biaryl backbone: the effects of the biaryl backbone and the substituent at oxazoline ring on Cu-catalyzed asymmetric cyclopropanation

The synthesis of novel C2-symmetric bisoxazoline ligands with an axial-unfixed biaryl backbone and different substituents at the oxazoline ring is reported. The diastereomer equilibrium of these ligands in solution and their complexation behavi

Catalytic asymmetric cyclopropanation of alkenes with diazoesters in protic and biphasic media

As a C2 symmetric hydrophilic chiral ligand, a series of 2,6-bis(oxazolinyl)-pyridines (pyboxs) bearing a hydroxyalkyl group on the oxazoline ring has been synthesized from readily available amino acid derivatives. Catalytic asymmetric intermolecular cyclopropanation of electron rich terminal alkenes with diazoesters in the presence of hydrophilic pybox ligand, pybox-hm and Ru(II) complex proceeded smoothly in protic or biphasic media to give the corresponding cyclopropanation products in 97:3 to 99:1 trans/cis ratios and 90 to 97% ee. In the case of the intramolecular cyclopropanation reaction of trans-cinnamyl diazoester using Ru(II)(pybox-he) complex in biphasic medium gave the corresponding cyclopropane ring fused lactone in 52% ee. Steric tuning of the chiral environment of pybox ligands was simply achieved by using a weak interaction between the solvent and the hydroxyl groups of the chiral ligand. The solubility of the new hydrophilic pybox and Ru(II) complexes in protic solvents is dramatically increased; hence, the efficiency of these catalysts enhanced the rate of cyclopropanation. Furthermore, the active catalyst in the water phase can be re-used several times for the cyclopropanation reaction.

A new chiral ruthenium complex for catalytic asymmetric cyclopropanation

A new chiral ruthenium complex 6, featured with an N,O-mixed polydentate ligand, was synthesized and characterized. This ruthenium complex showed high efficiency in catalytic cyclopropanations of alkenes with diazoacetates. High trans/cis selectivity and enantioselectivity (up to 96%) were achieved with the readily accessible ethyl diazoacetate as the reagent.

In search of high stereocontrol for the construction of cis-disubstituted cyclopropane compounds. Total synthesis of a cyclopropane-configured urea-PETT analogue that is a HIV-1 reverse transcriptase inhibitor.

[reaction: see text] A new azetidine-ligated dirhodium(II) catalyst that possesses a l-menthyl ester attachment provides significant diastereocontrol and high enantiocontrol for the formation of cis-cyclopropane products from reactions of substituted styr

Asymmetric cyclopropanation in protic media conducted by chiral bis(hydroxymethyl-dihydrooxazolyl)pyridine-ruthenium catalysts

Cyclopropanation of styrene with diazoacetates, performed in aqueous/organic biphasic media or homogeneous alcoholic media in the combination of toluene by using chiral bis(hydroxymethyldihydrooxazolyl)pyridine-ruthenium catalyst, resulted in high enantio

Asymmetric inter- and intramolecular cyclopropanation of alkenes catalyzed by chiral ruthenium porphyrins. Synthesis and crystal structure of a chiral metalloporphyrin carbene complex

Extensive investigations of asymmetric intermolecular cyclopropanation of terminal alkenes with diazoacetates catalyzed by ruthenium porphyrin [Ru(P*)(CO)(EtOH)] (1, H2P* = 5,10,15,20-tetrakis-{(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8- dimethanoanthracene-9-yl}porphyrin) and the application of catalyst 1 to asymmetric intramolecular cyclopropanation of allylic or homoallylic diazoacetates are described. The intermolecular cyclopropanation of styrene and its derivatives with ethyl diazoacetate afforded the corresponding cyclopropyl esters in up to 98% ee with high trans/cis ratios of up to 36 and extremely high catalyst turnovers of up to 1.1 × 104. Examination of the effects of temperature, diazoacetate, solvent, and substituent in the intermolecular cyclopropanation reveals that (i) both enantioselectivity and trans selectivity increase with decreasing temperature, (ii) sterically encumbered diazoacetates N2CHCO2R such as R = But, and donor solvents, such as diethyl ether and tetrahydrofuran, are beneficial to the trans selectivity, and (iii) electron-donating para substituents on styrene accelerate the cyclopropanations, with the log(kx/kH) vs σ+ plot for para-substituted styrenes p-X-C6H4CH=CH2 (X = MeO, Me, Cl, CF3) exhibiting good linearity with a small negative ρ+ value of -0.44 ± 0.09. In the case of intramolecular cyclopropanation, complex 1 promoted the decomposition of a series of allylic diazoacetates to form the cyclopropyl lactones in up to 85% ee, contributing the first efficient metalloporphyrin catalyst for an asymmetric intramolecular cyclopropanation. Both the inter- and intramolecular cyclopropanations were proposed to proceed via a reactive chiral ruthenium carbene intermediate. The enantioselectivities in these processes were rationalized on the basis of the X-ray crystal structures of closely related stable chiral carbene complexes [Ru(P*)(CPh2)] (2) and [Ru(P*)(C(Ph)-CO2CH2CH=CH2)] (3) obtained from reactions of complex 1 with N2CPh2 and N2C(Ph)CO2CH2CH=CH2, respectively.

Novel chiral bisoxazoline ligands with a biphenyl backbone: Preparation, complexation, and application in asymmetric catalytic reactions

Novel C2-symmetric chiral bisoxazoline ligands 1 were easily prepared from enantiomerically pure 2-amino alcohols and achiral 2,2′-biphenyldicarboxylic acid via the corresponding amide and mesylate as intermediates. Since these ligands bear only two ortho-substituents on the biphenyl backbone, the biphenyl axis is not fixed, and the two diastereomers of these ligands exist in equilibrium in solution. Interestingly, when the ligands 1 were coordinated with a metal ion, only one of the two possible diastereomer complexes, an (S,aS,S)-complex, can be formed depending on the combination of the ligand and the metal ion. Thus, copper(I) afforded only the (S,a,S,S)-complexes with all ligands 1, while zinc(II), palladium(II), and silver(I) afforded the (S,aS,S)-complexes as the sole product only with 1b, which has a bulky terf-butyl group on the oxazoline ring, and a mixture of the two diastereomer complexes with 1a,c,d. The copper(I)-catalyzed asymmetric cyclopropanation of styrene with diazoacetate proceeded successfully with these ligands and good to excellent enantioselectivities were afforded.

First enantioselective catalyst based on a chiral terpyridine: Synthesis of new C2-symmetric 2,2':6',2''-terpyridine ligands and copper-catalyzed enantioselective cyclopropanation of alkenes

New C2-symmetric chiral 2,2':6',2''-terpyridines were prepared from readily available homochiral materials. Copper complexes of these ligands were prepared in situ and their catalytic activities in cyclopropanations of alkenes with alkyl diazoacetate to give cyclopropyl esters were studied. In all cases, the cyclopropyl ester yields were excellent and enantioselectivities up to 94% ee were observed. Competition experiments revealed that electron-donating substituents on styrene accelerate the reaction. Hammett plot exhibited a good linearity with negative ρ+ value (-0.79). Copyright (C) 2000 Elsevier Science Ltd.

Asymmetric cyclopropanation of olefins with diazoacetate using chiral copper catalysts

Chiral 2-(2-aryl- or 2-alkyl-sufonylamino)phenyl-4-phenyl-1,3-oxazolines were found to be effective ligands for copper-catalyzed enantioselective cyclopropanation reaction of olefins. The reaction of styrene with d-menthyl diazoacetate in the presence of optically active copper catalysts gave cyclopropanation products in a ratio of trans: cis = 83: 17 with 63% ee (trans) and 84% ee (cis).