20488-50-0Relevant academic research and scientific papers
Carbonyl–Olefin Cross-Metathesis Through a Visible-Light-Induced 1,3-Diol Formation and Fragmentation Sequence
Pitzer, Lena,Sandfort, Frederik,Strieth-Kalthoff, Felix,Glorius, Frank
, p. 16219 - 16223 (2018/11/23)
A visible-light-mediated approach to carbonyl–olefin cross-metathesis is described. Photoinduced hole catalysis was used to promote the formation of 1,3-diols from aldehydes and styrenes, which were then readily fragmented under acidic conditions to form the cross-metathesis products. The use of 1,3-diols as intermediates, rather than the energetically more demanding oxetanes, provides a new, orthogonal mechanistic strategy for carbonyl–olefin cross-metathesis. Furthermore, this approach does not require any metals, ligands, or additives, and provides the products with high levels of E selectivity. A mechanistic rationale is provided and supported by both theoretical calculations and experiments. Additionally, a practical synthesis of a new acridinium-based photocatalyst, including full characterization, is presented.
Iron-catalyzed chemo- and stereoselective hydromagnesiation of diarylalkynes and diynes
Ilies, Laurean,Yoshida, Takumi,Nakamura, Eiichi
supporting information, p. 16951 - 16954,4 (2020/09/02)
Diarylalkynes are chemo- and stereoselectively hydromagnesiated in high yields at room temperature with an iron species generated in situ from FeCl 2and EtMgBr. Functional groups such as bromide, iodide, amine, phenoxide, and alkene are well tolerated. Under similar conditions, diynes are chemo-, regio-, and stereoselectively hydromagnesiated. The resulting alkenylmagnesium compounds are a platform for further functionalization as a one-pot reaction.
Regioselectice Trans-Cis Photoisomerization of m-Styrylstilbenes
Ito, Yoshikatsu,Uozu, Yoshihiro,Dote, Toshimichi,Ueda, Masahiro,Matsuura, Teruo
, p. 189 - 198 (2007/10/02)
Trans-cis photoisomerization of m-styrylstilbenes, i.e., 2,4,6-triisopropyl-3'-styrylstilbene (TISS), 2,4,6-trimethyl-3'-styrylstilbene (TMSS), and 3-styrylstilbene (SS), and of stilbenes, i.e., 2,4,6-triisopropylstilbene (TIS), 2,4,6-trimethylstilbene (TMS), and stilbene (S), are studied under direct or benzophenon-sensitized irradiation in hexane.Measurements of quantum yields for isomerization have revealed that although the styrylstilbene molecule bears two styryl groups, the reaction is highly regioselective, depending upon the excitation conditions and reactant structures.For example, isomerizations of trans,trans-TISS and trans,cis-TISS occured either at the 2,4,6-trisubstituted styryl side upon direct excitation or at the unsubstituted styryl side upon sensitized excitation.When the starting material carries an unsubstituted cis-styryl group, the major isomerization always occurred at this moiety by either direct or sensitized axcitation, e.g., cis,trans-TISS ---> trans,trans-TISS, cis,cis-TISS ---> trans,cis-TISS, and cis,trans-SS ---> trans,trans-SS.Furthermore, the photoisomerization of cis-SS was found to be one-way.These results are interpreted in terms of the usual "energy sink" concept: the excited-state energies (ES and ET) of the stilbene chromophores depend on molecular distortion in a subtle manner.It seems that an extremely rapid cis ---> trans isomerization rate of the unsubstituted cis-styryl group is also responsible for the observed preferential photoisomerization of this group.Finally, the cis,cis isomers of TISS, TMSS, and SS underwent upon sensitized excitation minor but substantial one-photon two-double-bond isomerization (cis,cis ---> trans,trans) in addition to major one-double-bond isomerization.This reaction is not common, since the two isomerizing double bonds are cross-conjugated.
Chemical Consequences of Single-Electron Oxidation of Phenylmesityldiazoethane
Little, Charles B.,Schuster, Gary B.
, p. 7167 - 7175 (2007/10/02)
Both thermolysis and photolysis of 1-phenyl-2-mesityldiazoethane (PMDE) lead exclusively to products derived from facile hydrogen or mesityl migration subsequent to, or concurrent with, loss of N2.No detectable amounts of ketazine or any dimeric hydrocarbons are formed in these reactions -a result that is attributable to the steric hindrance about the diazo carbon in PMDE.Quite in contrast, the one-electron oxidation of this diazoalkane yields no monomeric products by simple hydrogen or mesityl migration; instead, ketazine and dimeric products are formed by two distinct paths.Dimerization of diazo radical cations followed by competing secondary reactions of the resulting dication is the favored path according for the major products.In a very much slower reaction, PMDE+. attacks neutral PMDE to yield ketazine.
