Novel 1,3-dipolar cycloaddition of diazocarbonyl compounds to alkynes catalyzed by InCl3 in water
作者:Nan Jiang、Chao-Jun Li
DOI:10.1039/b311763d
日期:——
The first intermolecular 1,3-dipolar cycloaddition of diazocarbonylcompounds with alkynes was developed by using an InCl(3) catalyzed cycloaddition in water. The reaction was found to proceed by a domino 1,3-dipolar cycloaddition-hydrogen (alkyl or aryl) migration.
A series of new chiral binucleating pyrazolate-based N-donor ligands (3a-d) with oxazoline side arms (coined pyrbox's) have been synthesized. Bimetallic methallylpalladium complexes (4a-d) of these ligands were obtained, and the solid-state structures of complexes 4a,c were characterized by X-ray diffraction. NMR spectroscopy revealed that in solution 4a-d exist as three different isomers that differ in the orientation of the two methallyl ligands. Exchange between the isomers (i.e., allyl rotation) was observed in two-dimensional NOESY NMR experiments as syn/syn and anti/anti interconversion of the allylic hydrogen atoms; kinetic parameters for the fluxional behavior have been determined. The catalytic activity of the complexes was tested in palladium-catalyzed allylic alkylation of rac-(E)-1,3-diphenylallyl acetate. By comparison of the set of complexes 4a-d that feature different ligand scaffolds, both steric and electronic factors were found to be important for enantiocontrol, and a model has been proposed for rationalizing the observed enantioselectivities.
convenient synthetic procedures are reported for pyrazole derivatives with carbonyl or ester groups in the 3- and 5-positions and variable substitution pattern at C4 and at the functional side arms. All compounds have been characterized by 1 H and 13 C NMR spectroscopy, elemental analyses, and mass spectrometry. In addition, the structures of several pyrazole derivatives have been determined by single crystal
报告了一系列方便的合成方法,用于在 3 位和 5 位具有羰基或酯基团以及在 C4 和功能性侧臂处具有可变取代模式的吡唑衍生物。所有化合物均已通过 1 H 和 13 C NMR 光谱、元素分析和质谱进行了表征。此外,已经通过单晶 X 射线衍射确定了几种吡唑衍生物的结构,这有助于深入了解功能性侧臂对 NH-吡唑的氢键超分子基序的影响。