Steric Hindrance Facilitated Synthesis of Enynes and Their Intramolecular [4 + 2] Cycloaddition with Alkynes
摘要:
The palladium-catalyzed insertion of 1-alkynes into internal alkynes which are bent out of linearity by the interference with a peri or ortho substituent led to enynes regioselectively. The resulting enynes undergo a new type of intramolecular thermal cycloaddition, which can be used for the annulation of an aryl ring onto naphthalene derivatives to afford fluranthenes. The cyclization of (E)-1-(1-buten-3-ynyl)-8-ethynylnaphthalene could also be performed in the presence of a Cu(I) catalyst at room temperature.
A simple, cost-effective method for deuteration of carbonyl compounds employing pyrrolidine as catalyst and D2O as deuterium source was described. High degree of deuterium incorporation (up to 99%) and extensive functional group tolerance were achieved. It is the first time that secondary amines are used as catalysts for H/D exchange of carbonyl compounds, which also allow the deuteration of complex pharmaceutically interesting substrates. A possible catalytic mechanism, based on the hydrolysis of 1-pyrrolidino-1-cyclohexene, for this pyrrolidine-catalyzed H/D exchange reaction has been proposed.
Divergent Pd-catalyzed reactioncascades with various 1,3-diynamides yielding either 2-amino-3-alkynylindoles or 2-amino-4-alkenylquinolines were established. Omitting or adding TBAF (tetrabutylammonium fluoride) to the reaction of N,N-(2-iodophenyl)(4-toluenesulfonyl)-1,3-diynamides with secondary or primary amines in the presence of KOH in THF and catalytic amounts of Pd(PPh3)4 completely changed
From Theozymes to Artificial Enzymes: Enzyme-Like Receptors for Michael Additions with Oxyanion Holes and Active Amino Groups
作者:Luis Simón、Francisco M. Muñiz、Silvia Sáez、César Raposo、Joaquín R. Morán
DOI:10.1002/ejoc.200700565
日期:2007.10
Different artificial enzymes, based on the theozyme concept, have been designed for Michaeladditions of pyrrolidine to α,β-unsaturated lactams. These molecules each have skeleton able to mimic a structure called an “oxyanion hole”, as is present in many enzymes. Amine groups are also responsible for the catalytic activities of these receptors, since they support the important proton-transport step
Unexpected Resistance to Base-Catalyzed Hydrolysis of Nitrogen Pyramidal Amides Based on the 7-Azabicyclic[2.2.1]heptane Scaffold
作者:Diego Ocampo Gutiérrez de Velasco、Aoze Su、Luhan Zhai、Satowa Kinoshita、Yuko Otani、Tomohiko Ohwada
DOI:10.3390/molecules23092363
日期:——
of the base-catalyzedhydrolysis of 7-azabicyclo[2.2.1]heptane amides, which show pyramidalization of the amide nitrogen atom, and we compare the kinetics of the base-catalyzedhydrolysis of the benzamides of 7-azabicyclo[2.2.1]heptane and related monocyclic compounds. Unexpectedly, non-planar amides based on the 7-azabicyclo[2.2.1]heptane scaffold were found to be resistant to base-catalyzed hydrolysis
Distance Dependence of Bidirectional Concerted Proton-Electron Transfer in Phenol-Ru(2,2′-bipyridine)<sub>3</sub><sup>2+</sup>Dyads
作者:Jing Chen、Martin Kuss-Petermann、Oliver S. Wenger
DOI:10.1002/chem.201304256
日期:2014.4.1
of this bidirectionalconcertedproton–electrontransfer (CPET) reaction were studied as a function of phenol–Ru(bpy)32+ distance by increasing the number of bridging p‐xylene units. A distance decay constant (β) of 0.67±0.23 Å−1 was determined. The distancedependence of the rates for CPET is thus not significantly steeper than that for ordinary (i.e., not proton coupled) electron transfer across the