Stereo- and regiocontrol in ene-dimerisation and trimerisation of 1-trimethylsilyl-3-phenylcyclopropene

Intramolecular Alder-ene cycloisomerization of cyclopropenes with alkenes to access spirocycles

An Alder-ene cycloisomerization creates 3D-shaped spirocycles from cyclopropenes.

Mechanistic Insights into the Racemization of Fused Cyclopropyl Isoxazolines

Experimental and computational studies of the unexpected racemization of enantiopure fused cyclopropyl isoxazolines are reported. These studies offer insights into the mechanism of racemization, quantify the position of the transition state on the dipolar-diradical continuum, and establish a relationship between the structure and stability of this class of compounds. Experimental and computed energy barriers for racemization are also presented.

Indium Catalyzed Hydrofunctionalization of Styrene Derivatives Bearing a Hydroxy Group with Organosilicon Nucleophiles

Hydrofunctionalization is one of the most important transformation reactions of alkenes. Herein, we describe the development of an indium-triiodide-catalyzed hydrofunctionalization of alkenes bearing a hydroxy group using various types of organosilicon nucleophiles. Indium triiodide was the most effective catalyst, whereas typical Lewis acids such as TiCl₄, AlCl₃, and BF₃·OEt₂ were ineffective. Many functional groups were successfully introduced, and these resulted in yields of 31-86%. Various styrene derivatives were also applicable to this reaction. Mechanistic investigation revealed that the present hydrofunctionalization proceeded through Brønsted acid-catalyzed intramolecular hydroalkoxylation of alkenes followed by InI₃-catalyzed substitution reaction of cyclic ether intermediates.

β-Silyl styrene as a dienophile in the cycloaddition with 3,5-dibromo-2-pyrone for the total synthesis of (±)-pancratistatin

A new synthetic route to (±)-pancratistatin was devised utilizing β-silyl styrene as a dienophile in the cycloaddition with 3,5-dibromo-2-pyrone. The TMS group incorporated in the cycloadduct permitted a facile elimination process for the eventual installation of the C(1)-OH function. Subsequent transformations including Curtius rearrangement and Bischler-Napieralski reactions completed the total synthesis of (±)-pancratistatin.

Recent developments of cyclopropene chemistry

This critical review discusses recent developments in the field of cyclopropene chemistry. Although several excellent reviews that mainly focused on the thermolysis and pyrolysis as well as metal-mediated reactions of cyclopropenes have been published, significant new developments have also been achieved in recent years. This brand new review provides an overview of the progress from 2007 to 2011 on the syntheses and transformations of cyclopropenes as well as their related mechanistic studies (238 references).