3471-09-8

Upstream product

• 1138-47-2 trans-1,2-diphenylcyclopropane 
• 75765-74-1 (+)-trans-3,5-diphenyl-1-pyrazoline 
• 186581-53-3 diazomethane 
• 108-86-1 bromobenzene 
• 6783-05-7 trans-2-phenylvinylboronic acid 
• 17763-67-6 Phenyl triflate 
• 217634-41-8 (1R, 2R)-2-phenylcyclopropylboronic acid 
• 1138-48-3 cis-1,2-diphenylcyclopropane 
• 100-42-5 styrene 
• 908094-04-2 phenyldiazomethane 
• 20780-54-5 (S)-styrene oxide 
• 1666-17-7 benzaldehyde p-toluenesulfonylhydrazone 
• 100-52-7 benzaldehyde 
• 75142-62-0 benzaldehyde 2,4,6-tri-isopropylbenzenesulphonyl hydrazone 

Relevant academic research and scientific papers

A practical approach to stereodefined cyclopropyl-substituted heteroarenes using a Suzuki-type reaction

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.

Modular enantioselective synthesis of cis-cyclopropanes through self-sensitized stereoselective photodecarboxylation with benzothiazolines

Chiral cis-cyclopropanes are strained rigid analogues of alkyl chains, whose study and application are limited by their difficult synthesis. A modular approach from olefin materials is enabled by the discovery of the electron donor-acceptor (EDA) interaction between 2-substituted benzothiazolines and N-hydroxyphthalimide esters. These complexes are activated by visible light without photocatalysts, and the benzothiazoline reagent plays a triple role as a photoreductant, a stereoselective hydrogen-atom donor, and a Br?nsted acid. Beyond the enantioselective synthesis of cis-cyclopropanes, these results introduce benzothiazolines as accessible and easily tunable self-sensitized photoreductants.

Asymmetric Radical Process for General Synthesis of Chiral Heteroaryl Cyclopropanes

A highly efficient catalytic method has been developed for asymmetric radical cyclopropanation of alkenes with in situ-generated α-heteroaryldiazomethanes via Co(II)-based metalloradical catalysis (MRC). Through fine-tuning the cavity-like environments of newly-synthesized D2-symmetric chiral amidoporphyrins as the supporting ligand, the optimized Co(II)-based metalloradical system is broadly applicable to α-pyridyl and other α-heteroaryldiazomethanes for asymmetric cyclopropanation of wide-ranging alkenes, including several types of challenging substrates. This new catalytic methodology provides a general access to valuable chiral heteroaryl cyclopropanes in high yields with excellent both diastereoselectivities and enantioselectivities. Combined computational and experimental studies further support the underlying stepwise radical mechanism of the Co(II)-based olefin cyclopropanation involving α- and γ-metalloalkyl radicals as the key intermediates.

Asymmetric radical cyclopropanation of alkenes with in situ-generated donor-substituted diazo reagents via Co(II)-based metalloradical catalysis

Donor-substituted diazo reagents, generated in situ from sulfonyl hydrazones in the presence of base, can serve as suitable radical precursors for Co(II)-based metalloradical catalysis (MRC). The cobalt(II) complex of D2-symmetric chiral porphyrin [Co(3,5-DuBu-Xu(2'-Naph)Phyrin)] is an efficient metalloradical catalyst that is capable of activating different N-arylsulfonyl hydrazones for asymmetric radical cyclopropanation of a broad range of alkenes, affording the corresponding cyclopropanes in high yields with effective control of both diastereo- and enantioselectivity. This Co(II)-based metalloradical system represents the first catalytic protocol that can effectively utilize donor-type diazo reagents for asymmetric olefin cyclopropanation.

Electronically tuned chiral ruthenium porphyrins: Extremely stable and selective catalysts for asymmetric epoxidation and cyclopropanation

We report the use of three enantiomerically pure and electronically tuned ruthenium carbonyl porphyrin catalysts for the asymmetric cyclopropanation and epoxidation of a variety of olefinic substrates. The D4-symmetric ligands carry a methoxy, a methyl or a trifluoromethyl group at the 10-position of each of the 9-[anti-(1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene)]-substituents at the meso-positions of the porphyrin. Introduction of a CF 3-substituent in this remote position resulted in greatly improved catalyst stability, and turnover numbers of up to 7500 were achieved for cyclopropanation, and up to 14200 for epoxidation, with ee values typically >90% and ≈80%, respectively. In one example, the axial CO ligand at the ruthenium was exchanged for PF3, resulting in the first chiral ruthenium porphyrin with a PF3 ligand reported to date. In cyclopropanations with ethyl diazoacetate, the latter catalyst performed exceedingly well, and gave a 95% ee in the case of 1,1-diphenylethylene as substrate.

Cyclodextrin mediated enantio and diastereoselective geometric photoisomerization of diphenylcyclopropane and its derivatives

cis-Diphenylcyclopropanes upon direct excitation and triplet sensitization undergo geometric isomerization to the corresponding trans isomers. In solution the trans isomers are formed as a 1:1 enantiomeric or diasteromeric mixture. Upon inclusion within β-cyclodextrin the same molecules give the trans isomers enriched in one optical isomer. Enantiomeric excess and diasteromeric excess induced by the optically active host β-cyclodextrin although small is mechanistically significant.

Palladium-catalyzed cross-coupling reaction of cyclopropylboronic acids with aryl triflates

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.

Enantioselective synthesis of γ-hydroxysilanes, 1,3-diols and cyclopropanes by reaction of a chiral epoxide with a racemic α-silyl organolithium reagent

The racemic α-silyl organolithium reagents 2a and 2b react with (R)-styrene oxide enantioselectively to produce the chiral γ-hydroxysilanes 3a and 3b, respectively. The chiral 1,3-diol 4 and cyclopropane 7 are readily obtained in enantiomerically pure form from these γ-hydroxysilanes.