Remarkable effect of tris(4-fluorophenyl)phosphine oxide on the stabilization of chiral lanthanum complex catalysts. A new and practical protocol for the highly enantioselective epoxidation of conjugated enonesElectronic supplementary information (ESI) available: HPLC analysis of 2, 1H NMR data for 3 and 4, and crystal data for 5. See http://www.rsc.org/suppdata/ob/b4/b405882h/
An extract of whole plants of Pycnanthemum flexuosum showed an inhibitory effect on hyaluronidase activity. From an 80% acetone extract of aerial parts, 3-[(3E)-4-phenylbut-3-enoylamino]propionic acid, 3-O-β-d-glucuronopyranosyl-echinocystic acid 28-O-β-d-xylopyranosyl-(1→3)-[3,4-diacetyl-β-d-xylopyranosyl-(1→4)]-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl ester, vanillic acid 1-O-[(5-O-syringoyl)-β-d-apiofuranosyl]-(1→2)-β-d-glucopyranoside, and (4S,5R)-4-hydroxy-5-phenyl-tetrahydrofuran-2-one were isolated together with 30 known compounds. Six known compounds were isolated from an 80% acetone extract of roots, and eritrichin was revealed as a hyaluronidase inhibitor in P. flexuosum.
Remarkable effect of tris(4-fluorophenyl)phosphine oxide on the stabilization of chiral lanthanum complex catalysts. A new and practical protocol for the highly enantioselective epoxidation of conjugated enonesElectronic supplementary information (ESI) available: HPLC analysis of 2, 1H NMR data for 3 and 4, and crystal data for 5. See http://www.rsc.org/suppdata/ob/b4/b405882h/
A new and efficient chiral catalyst system, lanthanum–chiral BINOL–tris(4-fluorophenyl)phosphine oxide–cumene hydroperoxide, was developed for the epoxidation of α,β-unsaturated ketones thus providing the corresponding epoxy ketones with excellent enantioselectivities (up to >99% ee) in good to excellent yields at room temperature.
Enantioselective Epoxidation of β,γ-Unsaturated Carboxylic Acids by a Cooperative Binuclear Titanium Complex
作者:Takahiro Sawano、Hisashi Yamamoto
DOI:10.1021/acscatal.9b00840
日期:2019.4.5
Enantioselective epoxidation of β,γ-unsaturated carboxylicacids with a cooperative binuclear titanium complex has been developed to provide single diastereomer γ-lactones in high yields and enantioselectivities via intramolecular cyclization. For the success of the reaction, the proper distance between the carboxylicacid and alkene is quite important, offering the regioselective epoxidation of unsaturated