The use of the hypervalentiodinereagents in oxidative processes has become a staple in modern organic synthesis. Frequently, the reactivity of λ3 iodanes is further enhanced by acids (Lewis or Brønsted). The origin of such activation, however, has remained elusive. Here, we use the common combination of PhI(OAc)2 with BF3·Et2O as a model to fully explore this activation phenomenon. In addition to
Synthesis of Naphthylpyridines from Unsymmetrical Naphthylheptadiynes and the Configurational Stability of the Biaryl Axis
作者:Fabian Fischer、Alexander F. Siegle、Marek Checinski、Christine Fischer、Karolin Kral、Richard Thede、Oliver Trapp、Marko Hapke
DOI:10.1021/acs.joc.5b02190
日期:2016.4.15
cycloaddition reaction between the corresponding naphthyldiyne and aceto- or benzonitrile. The heterobiaryl products have been isolated and investigated with respect to the configurational stability of their biaryl axis using dynamic chiral HPLC; subtle effects of the substitution pattern on the stability of the axis were observed. For several compounds the activation barriers (ΔG‡) of racemization were determined
reactions starting from the chiral auxiliary p-menthane-3-carboxaldehyde. The key feature of the sequence is a highlyselective tandem Mitsunobu/3,3-sigmatropic rearrangement of hydrazoic acid that procures enantiomericallyenriched allylic azides. The sequence is either terminated by oxidative cleavage to provide amino acids or by ring-closing metathesis to provide heterocycles or carbocycles bearing nitrogen
On the mechanism of nucleophilic substitution of allenyl(aryl)iodine(III): Formation of propargyl cation and competition with sigmatropic rearrangement
作者:Masahito Ochiai、Michio Kida、Tadashi Okuyama
DOI:10.1016/s0040-4039(98)01276-3
日期:1998.8
The ratios of nucleophilicsubstitution versus [3,3] sigmatropic rearrangement for the collapse of allenyl(aryl)-iodine(III), generated from the reaction of aryliodanes with propargylsilanes in the presence of BF3Et2O in alcohols, were determined. A proposed mechanism involves generation of propargyl cations from the allenyliodine(III) via a unimolecular pathway.
iodinanes, which undergo [3,3]-sigmatropic rearrangement. The lack of crossover products argues for the intramolecularity of the rearrangement. When both ortho positions of aryliodinanes are occupied with alkyl substituents, the reductive iodonio-Claisen rearrangement affords meta substitution products. This is the first to show that meta-Claisen rearrangementoccurs preferentially even when a free para