5307-05-1Relevant articles and documents
Enantioselective Cleavage of Cyclobutanols Through Ir-Catalyzed C?C Bond Activation: Mechanistic and Synthetic Aspects
Ratsch, Friederike,Strache, Joss Pepe,Schlundt, Waldemar,Neud?rfl, J?rg-Martin,Adler, Andreas,Aziz, Sarwar,Goldfuss, Bernd,Schmalz, Hans-Günther
supporting information, p. 4640 - 4652 (2021/02/11)
The Ir-catalyzed conversion of prochiral tert-cyclobutanols to β-methyl-substituted ketones proceeds under comparably mild conditions in toluene (45–110 °C) and is particularly suited for the enantioselective desymmetrization of β-oxy-substituted substrates to give products with a quaternary chirality center with up to 95 % ee using DTBM-SegPhos as a chiral ligand. Deuteration experiments and kinetic isotope effect measurements revealed major mechanistic differences to related RhI-catalyzed transformations. Supported by DFT calculations we propose the initial formation of an IrIII hydride intermediate, which then undergoes a β-C elimination (C?C bond activation) prior to reductive C?H elimination. The computational model also allows the prediction of the stereochemical outcome. The Ir-catalyzed cyclobutanol cleavage is broadly applicable but fails for substrates bearing strongly coordinating groups. The method is of particular value for the stereo-controlled synthesis of substituted chromanes related to the tocopherols and other natural products.
Para -Selective hydroxylation of alkyl aryl ethers
Zhu, Runqing,Sun, Qianqian,Li, Jing,Li, Luohao,Gao, Qinghe,Wang, Yakun,Fang, Lizhen
supporting information, p. 13190 - 13193 (2021/12/16)
para-Selective hydroxylation of alkyl aryl ethers is established, which proceeds with a ruthenium(ii) catalyst, hypervalent iodine(iii) and trifluoroacetic anhydride via a radical mechanism. This protocol tolerates a wide scope of substrates and provides a facile and efficient method for preparing clinical drugs monobenzone and pramocaine on a gram scale.
Tripodal O-N-O Bis-Phenolato Amine Titanium(IV) Complexes Show High in vitro Anti-Cancer Activity
Abid, Mohammed,Nouch, Ryan,Bradshaw, Tracey D.,Lewis, William,Woodward, Simon
supporting information, p. 2774 - 2780 (2019/06/13)
The octahedral titanium(IV) complexes trans,mer-[Ti{R3N(CH2C6H2-2-O-4-R2-6-R1)2}2] (R1 = Me, OMe, Cl; R2 = Me, OMe, F, Cl; R3 = Me, Et; not all combinations) are synthesised in two steps from simple phenols in 36–53 % overall yield. The highly crystalline (4 X-ray structures) complexes are active against MCF-7 (breast) and HCT-116 (colon) cancer cell lines showing widely varying GI50 values in the range 1–100 μM depending on R1–R3. Highest activities are realised when R1 = OMe and R2, R3 = Me (GI50 ca. 1 μM for MCF-7 and 2–3 μM for HCT-116). These are respectively 8× and 3× times greater than the activities of cisplatin in the same cell lines. These titanium complexes show some significant selectivity for cancer cell lines; up to 7× higher in MCF-7 compared to non-cancer (MRC-5) fibroblast cells. Details of cellular mode of action indicators (cell cycle perturbation, Annexin V, γ-H2AX, and caspase studies) that point to an apoptosis mode for the most active compound (R1 = OMe and R2, R3 = Me) are also reported.||||||.