Self-Isomerized-Cyclometalated Rhodium NHC Complexes as Active Catalysts in the Hydrosilylation of Internal Alkynes was written by van Vuuren, Estefan;Malan, Frederick P.;Cordier, Werner;Nell, Margo;Landman, Marile. And the article was included in Organometallics in 2022.HPLC of Formula: 16356-02-8 This article mentions the following:
A range of unique Rh-based bidentate NHC complexes that are formed in a base free-tandem isomerization/cyclometalation process, were synthesized (1–4) from a range of imidazolium salts with an N-alkenyl tether. Cyclometalation occurred with complex 1 leading to an unprecedented complex, which is the 1st and only example in literature of a nonaromatic C(sp2)-H activation leading to a C(sp3)-Rh cyclometalated product with a concomitant intramol./isomerization process. Dealkylation of the N-alkenyl substituent occurred to form byproducts that showed metal N-coordination (1b and 2b). These byproducts, 1b and 2b, were further reacted with the anion exchange reagent NH4PF6 to form the dimeric complexes 1bd and 2bd. All the complexes were applied as precatalysts in the hydrosilylation of internal alkynes with excellent performance (conversions of 66-100%) after only 1 h at 80° without the use of an additive. Anticancer studies showed that complexes presented with half-maximal inhibitory concentrations ranging from 3.71 to 25.85μM. Depending on the cell line, complex 4 was the most cytotoxic complex, especially in the BT-20 triple-neg. breast carcinoma, MCF-12A nontumorigenic mammary gland cell, MDA-MB-231 triple-neg. breast carcinoma and MCF-7/TAMR-1 tamoxifen-resistant subtype of the MCF-7 estrogen- and progesterone-pos. luminal breast carcinoma cell lines. In the experiment, the researchers used many compounds, for example, 1,4-Dimethoxy-2-butyne (cas: 16356-02-8HPLC of Formula: 16356-02-8).
1,4-Dimethoxy-2-butyne (cas: 16356-02-8) belongs to ethers. The oxygen atom in ethers are more electronegative than carbon, thus the hydrogens which are alpha to the ethers are more acidic than the simple hydrocarbons. Electron-deficient reagents are also stabilized by ethers. For example, borane (BH3) is a useful reagent for making alcohols. Pure borane exists as its dimer, diborane (B2H6), a toxic gas that is inconvenient and hazardous to use. Borane forms stable complexes with ethers, however, and it is often supplied and used as its liquid complex with tetrahydrofuran (THF).HPLC of Formula: 16356-02-8