74254-17-4

Upstream product

• 1530-32-1 ethyltriphenylphosphonium bromide 
• 105-07-7 4-cyanobenzaldehyde 
• 74254-13-0 (E)-4-(prop-1-en-1-yl)benzonitrile 
• 1754-88-7 ethylenetriphenylphosphorane 

Relevant academic research and scientific papers

A Stereoconvergent Cyclopropanation Reaction of Styrenes

The first stereoconvergent cyclopropanation reaction by means of photoredox catalysis using diiodomethane as the methylene source is described. This transformation exhibits broad functional group tolerance and it is characterized by an excellent stereocontrol en route to trans-cyclopropanes regardless of whether E- or Z-styrene substrates were utilized.

Shifting Chemical Equilibria in Flow - Efficient Decarbonylation Driven by Annular Flow Regimes

To efficiently drive chemical reactions, it is often necessary to influence an equilibrium by removing one or more components from the reaction space. Such manipulation is straightforward in open systems, for example, by distillation of a volatile product from the reaction mixture. Herein we describe a unique high-temperature/high-pressure gas/liquid continuous-flow process for the rhodium-catalyzed decarbonylation of aldehydes. The carbon monoxide released during the reaction is carried with a stream of an inert gas through the center of the tubing, whereas the liquid feed travels as an annular film along the wall of the channel. As a consequence, carbon monoxide is effectively vaporized from the liquid phase into the gas phase and stripped from the reaction mixture, thus driving the equilibrium to the product and preventing poisoning of the catalyst. This approach enables the catalytic decarbonylation of a variety of aldehydes with unprecedented efficiency with a standard coil-based flow device.

Enantioselective nickel-catalyzed hydrocyanation of vinylarenes using chiral phosphine-phosphite ligands and TMS-CN as a source of HCN

Anti-headache chemistry: In the presence of a tailored modular P,P ligand the nickel-catalyzed addition of HCN, generated in situ from TMS-CN, to styrene derivatives proceeds with an unprecedented level of stereocontrol (up to 97 % ee) to give 2-aryl-acetonitriles, for example, the depicted precursor of Ibuprofen. Copyright

Singlet state Cis,Trans photoisomerization and intersystem crossing of 1-arylpropenes

The temperature dependence of the singlet state lifetime and photoisomerization and fluorescence quantum yields for trans- and cis-1-phenylpropene have been determined in hexane solution. Calculated barriers for twisting about the double bond on the singlet potential energy surface are 8.8 and 4.6 kcal/mol for the trans and cis isomer, respectively. The barrier for the trans isomer is sufficiently high to prevent isomerization on the singlet state surface at or below room temperature. However, isomerization occurs at low temperatures as a consequence of intersystem crossing to the triplet state, which undergoes barrierless isomerization. The quantum yield for intersystem crossing, as determined by time-resolved photoacoustic calorimetry, is 0.60 ± 0.03 and the rate constant for intersystem crossing is 4.7 × 107 s-1. While internal conversion is not significant at or below room temperature, thermally activated internal conversion competes with singlet isomerization at high temperatures. The cis isomer undergoes isomerization predominantly via the singlet state at room temperature. Both electron-donating (p-methoxy) and electron-withdrawing (m- and p-cyano, p-carbomethoxy, and p-trifluormethyl) aromatic substituents are found to lower the barrier for singlet state isomerization. Increased solvent polarity (acetonitrile vs hexane) results in variable decreases in the barrier for singlet state isomerization. Photoisomerization of the p-cyano derivative at room temperature occurs predominantly via the triplet state in hexane solution and via the singlet state in acetonitrile solution. The effects of substituents and solvent are better correlated with the magnitude of the S2-S1 energy gap than the stability of either zwitterionic or biradical intermediates. Rate constants for intersystem crossing are, in most cases, not highly dependent upon aromatic substitution or solvent polarity.

WITTIG-REAKTION VON TRIPHENYLPHOSPHONIO-ALKYLIDEN MIT SUBSTITUIERTEN BENZALDEHYDEN: HAMMETT-BEZIEHUNG UND TEILWEISE REVERSIBILITAT DER ADDUKT-BILDUNG

Bei Abwesenheit loslicher Lithium-Salze vereinigen sich Triphenylphosphonio-methylid und -ethylid bereits bei -75 deg C mit Aldehyden. Elektronenanziehende Liganden beschleunigen, elektronenspendende Liganden verzogern die Anlagerung der Ylide an die substituierten Benzaldehyde.Die Addukte(Oxaphosphetane) zerfallen erst oberhalb -30 deg C zu Olefin und Triphenylphosphinoxid.Wird vor dem Zerfall ein zweiter Aldehyd oder ein zweites Ylid zugesetzt, so findet ein teilweiser Austausch der Komponenten statt.