110163-89-8Relevant academic research and scientific papers
Temperature-dependent photochemistry of 1,3-diphenylpropenes. The di-π-methane reaction revisited
Lewis,Zuo,Kalgutkar,Wagner-Brennan,Miranda,Font-Sanchis,Perez-Prieto
, p. 11883 - 11889 (2001)
The temperature-dependent photochemical behavior of 1,3-diphenylpropene and several of its 3-substituted derivatives has been investigated over a wide temperature range. The singlet state is found to decay via two unactivated processes, fluorescence and intersystem crossing, and two activated processes, trans,-cis isomerization and phenyl-vinyl bridging. The latter activated process yields a diradical intermediate which partitions between ground-state reactant and formation of the di-π-methane rearrangement product. Kinetic modeling of temperature-dependent singlet decay times and quantum yields of fluorescence, isomerization, di-π-methane rearrangement, and nonradiative decay provides rate constants and activation parameters for each of the primary and secondary processes. Substituents at the 3-position are found to have little effect on the electronic spectra or unactivated fluorescence and intersystem crossing pathways. However, they do effect the activated primary and secondary processes. Thus, the product ratios are highly temperature dependent.
A Ligand-Free Pt3Cluster Catalyzes the Markovnikov Hydrosilylation of Alkynes with up to 106Turnover Frequencies
Rivero-Crespo, Miguel A.,Leyva-Pérez, Antonio,Corma, Avelino
, p. 1702 - 1708 (2017/02/10)
The Pt-catalyzed hydrosilylation of alkynes is the procedure of choice to obtain vinylsilanes, and is claimed to be the most relevant application of Pt in organic synthesis. More than half a century after its discovery, only β-vinylsilanes (anti-Markovnikov addition) are obtained with simple Pt catalysts, whereas α-vinylsilanes (Markovnikov addition) remain elusive compounds. Here the catalysis of the Markovnikov hydrosilylation of terminal alkynes by Pt3clusters, in parts-per-million amounts, to give a wide variety of α-vinylsilanes in reasonable isolated yields and with turnover frequencies that can reach up to one million per hour is reported. Moreover, these α-vinylsilanes are reactive in well-stablished C?C bond-forming cascade reactions, in which the corresponding β-isomers are unreactive. Besides its efficiency and synthetic usefulness, this catalytic system is an excellent example of how the atom-by-atom aggregation of a catalytic metal leads to a different selectivity for a given reaction.
