Examination of subsequent reaction products enhanced through parahydrogen-induced nuclear polarization (PHIP)
摘要:
Homogeneous hydrogenation with parahydrogen yields strong nuclear spin polarization in the H-1 NMR spectra of the reaction products. This polarization can be transferred to subsequent reaction products and detected by in situ H-1 MMR spectroscopy. As a typical example, the hydrogenation of 1-phenylpropyne with parahydrogen generates the spin-polarized molecule 1-phenylpropene. Upon bromination of this product, its polarization is transferred to the reaction product 1,a-dibromo-l-phenylpropane. As a second example, polarization was observed in the addition product of DBr to spin-polarized dimethyl maleate which is generated from dimethyl acetylenedicarboxylate by addition of parahydrogen. Copyright (C) 2000 John Wiley & Sons, Ltd.
Synthesis of [<i>m.n</i>]Cyclophanes: Regiochemistry Transfer from Vinyl Halides to Cyclophanes via Fischer Carbene Complexes
作者:Huan Wang、Alexander V. Predeus、William D. Wulff
DOI:10.1002/chem.201204434
日期:2013.6.17
and para bridges. The connectivity patterns of the bridges in the cyclophanes can be controlled by regioselectivity transfer from the bis‐vinyl carbenecomplexes in which the substitution pattern of the vinyl groups in the carbenecomplexes dictate the connectivity pattern in the [m.n]cyclophanes. This synthesis of [n.n]cyclophanes is quite flexible with regard to ring size and can be used with tether
Homogeneous hydrogenation with parahydrogen yields strong nuclear spin polarization in the H-1 NMR spectra of the reaction products. This polarization can be transferred to subsequent reaction products and detected by in situ H-1 MMR spectroscopy. As a typical example, the hydrogenation of 1-phenylpropyne with parahydrogen generates the spin-polarized molecule 1-phenylpropene. Upon bromination of this product, its polarization is transferred to the reaction product 1,a-dibromo-l-phenylpropane. As a second example, polarization was observed in the addition product of DBr to spin-polarized dimethyl maleate which is generated from dimethyl acetylenedicarboxylate by addition of parahydrogen. Copyright (C) 2000 John Wiley & Sons, Ltd.
The First Examples of a <i>Meta</i>-Benzannulation from the Reaction of Fischer Carbene Complexes with Alkynes
作者:Huan Wang、Jie Huang、William D. Wulff、Arnold L. Rheingold
DOI:10.1021/ja035428n
日期:2003.7.1
intramolecular benzannulations of carbene complexes with alkynes are examined where the alkyne is tethered to the alpha-carbon of the vinyl carbene complex. These reactions are sensitive to the length of the tether and to the nature of the solvent. With a tether length of 16 methylenes, the reaction occurs in the same fashion as the intermolecular reactions to give a p-cyclophane. With intermediate