Synthesis and application of β-substituted Pauson-Khand adducts: trifluoromethyl as a removable steering group.

The reaction between alkynes (I) and norbornadiene (II) affords the β-substituted Pauson—Khand adducts (III) as single regioisomers and the trifluoromethyl steering group can be easily removed in the presence of DBU and water.

Innentitelbild: Synthesis and Application of β-Substituted Pauson-Khand Adducts: Trifluoromethyl as a Removable Steering Group (Angew. Chem. 20/2013)

Inside Cover: Synthesis and Application of β-Substituted Pauson-Khand Adducts: Trifluoromethyl as a Removable Steering Group (Angew. Chem. Int. Ed. 20/2013)

Pauson-Khand reaction of internal dissymmetric trifluoromethyl alkynes. Influence of the alkene on the regioselectivity.

Abstract: The scope of the Pauson-Khand reaction (PKR) of internal trifluoromethyl alkynes, previously described with norbornadiene, is expanded to norbornene and ethylene. A thorough structural analysis of the resulting PK adducts has been carried out to unveil that α-trifluoromethylcyclopentenones are preferred in all cases, independently of the electronic properties of the alkyne. The regioselectivity observed with norbornadiene and ethylene is higher than in the case of norbornene.

CCDC 927146: Experimental Crystal Structure Determination

Related Article: Nuria Aiguabella, Carlos del Pozo, Xavier Verdaguer, Santos Fustero, Antoni Riera|2013|Angew.Chem.,Int.Ed.|52|5355|doi:10.1002/anie.201300907