Fluorous Effects in Amide-Based Receptors for Anions
作者:Jesse V. Gavette、Jacqueline M. McGrath、Anne M. Spuches、Andrew L. Sargent、William E. Allen
DOI:10.1021/jo9000788
日期:2009.5.15
1H NMR and isothermaltitrationcalorimetry (ITC). In chloroform solvent, hydrogen-bonding to anions is accompanied by downfield shifts in the amide NH protons of the fluorinated receptors and by evolution of heat. Association constants for 1:1 complexation (Kassoc) are >1000 M−1. An analogous hydrocarbon receptor binds weakly to anionic guests (Kassoc < 50 M−1). Abinitiocalculations indicate that
杂合受体设计成识别磺酸盐首基和全氟辛烷的氟尾部两者(CF 3(CF 2)7 SO 3 -,“PFOS”)通过偶合氟化羧酸在聚(氨基甲基)苯的支架制备。结合PFOS,CF 3 SO 3 - ,p -TsO -和Cl -通过监测1 H NMR和等温滴定量热法(ITC)。在氯仿溶剂中,氢键阴离子在酰胺N被伴随着低磁场位移ħ氟化受体的质子和热量的释放。1:1络合(K assoc)的缔合常数> 1000 M -1。类似的烃受体与阴离子客体的结合较弱(K assoc <50 M -1)。从头算计算表明,氟和非氟主体之间1:1结合强度的差异不能归因于N H供体酸度的差异。
Solvent and H/D Isotope Effects on the Proton Transfer Pathways in Heteroconjugated Hydrogen-Bonded Phenol-Carboxylic Acid Anions Observed by Combined UV–vis and NMR Spectroscopy
作者:Benjamin Koeppe、Jing Guo、Peter M. Tolstoy、Gleb S. Denisov、Hans-Heinrich Limbach
DOI:10.1021/ja400611x
日期:2013.5.22
states. It is shown that the (13)Cchemicalshifts of the phenolic residues of A···H···X(-), referenced to the corresponding values of A···H···A(-), constitute excellent probes for the average proton positions. These shifts correlate with those of the H-bonded protons, as well as with the H/D isotope effects on the (13)Cchemicalshifts. A combined analysis of UV-vis and NMR data was employed to elucidate
PROCESSES OF ENANTIOSELECTIVELY FORMING AN AMINOXY COMPOUND AND AN 1,2-OXAZINE COMPOUND
申请人:Zhong Guofu
公开号:US20110224429A1
公开(公告)日:2011-09-15
Disclosed is a process of enantioselectively forming an aminoxy compound of Formula (3)
In formula (3) R
1
is one of an aliphatic group and an alicyclic group. R
2
is one of hydrogen, an aliphatic group, an alicyclic group, an aromatic group, an arylaliphatic group and an arylalicyclic group. R
3
is one of hydrogen, halogen, hydroxyl, and an aliphatic group with a main chain having 1 to about 10 carbon atoms. The respective aliphatic, alicyclic, aromatic, arylaliphatic or arylalicyclic groups of R
1
, R
2
, and R
3
comprise 0 to about 3 heteroatoms independently selected from the group consisting of N, O, S, Se and Si. The process includes contacting a carbonyl compound of Formula (1)
and a nitroso compound of Formula (2)
in the presence of a chiral catalyst. The chiral catalyst is a compound of Formula (IX)
also obtained in a minor fraction in unbuffered methanol, ethanol, and acetic acid, but not in trifluoroethanol or hexafluoro-2-propanol: the methoxy product from methanolysis is largely racemized, but the acetolysis product is obtained mainly via retention of configuration. Reactions of 1 with bromide, acetate, and trifluoroacetate in chloroform give unrearranged substitution products in different
Nonheme Oxoiron(IV) Complexes of Tris(2-pyridylmethyl)amine with <i>cis</i>-Monoanionic Ligands
作者:Jan-Uwe Rohde、Audria Stubna、Emile L. Bominaar、Eckard Münck、Wonwoo Nam、Lawrence Que
DOI:10.1021/ic060740u
日期:2006.8.1
Treatment of [Fe(IV)(O)(TPA)(NCMe)](CF3SO3)2 [TPA, N,N,N-tris(2-pyridylmethyl)amine] with 3 equiv of NR4X (X = CF3CO2, Cl, or Br) in MeCN at -40 degrees C affords a series of metastable [Fe(IV)(O)(TPA)(X)]+ complexes. Some characteristic features of the S = 1 oxoiron(IV) unit are quite insensitive to the ligand substitution in the equatorial plane, namely, the Fe-O distances (1.65-1.66 A), the energy