(o-Hydroxyphenyl)methylphosphonic acids are readily obtained from o-(bromomethyl)- or o-(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pKavalues have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric
从邻-(溴甲基)-或邻-(羟甲基)酚和亚磷酸三烷基酯容易获得(邻-羟基苯基)甲基膦酸。随后的水解产生相应的膦酸。对于一系列此类化合物,p K a值已通过电位计确定。根据电子和空间效应,讨论了它们对芳环中其他取代基的依赖性。
Catalytic compositions and methods for asymmetric aldol reactions
申请人:——
公开号:US20020147367A1
公开(公告)日:2002-10-10
Methods and compositions are provided for the direct catalytic asymmetric aldol reaction of aldehydes with donor molecules selected from ketones and nitroalkyl compounds. The reactions employ as catalyst a Group 2A or Group 2B metal complex of a ligand of formula I, as defined further herein.
1
(ICEs) with a similar cavity architecture have the alternating polarity of cationic metal ring and encapsulated ion to construct the skeleton. Here we introduce a new tridentate aryloxide-N-heterocyclic carbene ligand to stabilize μ4-oxo [Mg4O] cores in ICEs, which open up a path towards synthetic methodology for ICEs. The reaction of N-Heterocycliccarbene (NHC) lithium complex (L)Li2(L1) (1; L=1-C(N
Development of Bis(2-picolyl)amine–Zinc Chelates for Imidazole Receptors
作者:Taina Routasalo、Juho Helaja、Jari Kavakka、Ari M. P. Koskinen
DOI:10.1002/ejoc.200700926
日期:2008.6
phenol bis(2-picolyl)amine (Dpa) derivatives have been synthesized in order to generate zinc chelates for imidazole anion receptors. Previously, binuclear phenolic zinc and copper chelates have shown affinity for pyrophosphate and guanidine anions, respectively. Herein we report significant imidazole affinity increasing from 2.38 × 106 to 2.90 × 107 for phenol-bridged binuclear zinc–Dpa chelates, as evidenced
A chromogenic reagent for calcium. The importance of ion-pairing in cation selection
作者:Andrew Mason、Ian O. Sutherland
DOI:10.1039/c39940001131
日期:——
The chromoionophore 2 has been synthesised from the corresponding diaza 18-crown-6 in two steps in good overall yield, and the reagent 2 extracts calcium cations from aqueous solutions in the pH range 7–9 with moderately high selectivity as compared with sodium and with high selectivity as compared with other cations of biological interest; the series of apparently similar reagents 2, 3 and 4 shows very wide variation in Na+/Ca2+ selectivity.