Oxorhenium(V) complexes with naphtholate-oxazoline ligands in the catalytic epoxidation of olefins
摘要:
Four oxorhenium(V) complexes 3a-d equipped with naphtholate-oxazoline based ligands 2a-d have been prepared and characterized by NMR, IR and mass spectroscopy as well as elemental analysis. Ligands 2a-d were prepared in a two-step procedure from commercially available starting materials. Ligands 2a-b and 2c-d are regioisomers to each other regarding the position of the -OH group and oxazoline moiety on the naphthol ring. Reaction of 2a-d with (NBu4)[ReOCl4] in methanol under reflux gave oxorhenium(V) complexes 3a-d of the type [ReOCl(L)(2)] as green solids in acceptable to good yields. The molecular structures of complexes 3b and 3d have been determined via single crystal X-ray diffraction analysis and both display a distorted octahedral geometry. Complexes 3a-d are active catalysts for the epoxidation of cyclooctene with tert-butylhydroperoxide (TBHP) showing moderate conversions between 41% and 65%. (C) 2014 Elsevier Ltd. All rights reserved.
Oxorhenium(V) complexes with naphtholate-oxazoline ligands in the catalytic epoxidation of olefins
摘要:
Four oxorhenium(V) complexes 3a-d equipped with naphtholate-oxazoline based ligands 2a-d have been prepared and characterized by NMR, IR and mass spectroscopy as well as elemental analysis. Ligands 2a-d were prepared in a two-step procedure from commercially available starting materials. Ligands 2a-b and 2c-d are regioisomers to each other regarding the position of the -OH group and oxazoline moiety on the naphthol ring. Reaction of 2a-d with (NBu4)[ReOCl4] in methanol under reflux gave oxorhenium(V) complexes 3a-d of the type [ReOCl(L)(2)] as green solids in acceptable to good yields. The molecular structures of complexes 3b and 3d have been determined via single crystal X-ray diffraction analysis and both display a distorted octahedral geometry. Complexes 3a-d are active catalysts for the epoxidation of cyclooctene with tert-butylhydroperoxide (TBHP) showing moderate conversions between 41% and 65%. (C) 2014 Elsevier Ltd. All rights reserved.
Aerobic C(sp<sup>2</sup>)–H Hydroxylations of 2-Aryloxazolines: Fast Access to Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
作者:Dominik Göbel、Nils Clamor、Enno Lork、Boris J. Nachtsheim
DOI:10.1021/acs.orglett.9b01350
日期:2019.7.19
The direct hydroxylation of 2-aryloxazolines via a deprotonative magnesiation using TMPMgCl center dot LiCl and subsequent oxidation with molecular oxygen or air as a green oxidant is reported. This method proceeds under mild conditions at room temperature with high regioselectivity and chemoselectivity. The obtained phenols exhibit tunable luminescence properties, induced by excited-state intramolecular proton transfer. This method opens a new opportunity for the sustainable synthesis of luminescent organic molecules.