Palladium-catalyzed vinylation of cyclohexenes using a directing-group strategy

Palladium-promoted vinylation of cyclohexenes via employment of a directing-group strategy to yield the coupled vinyl cyclohexenes with excellent regio- and stereoselectivity was studied. Typically, reaction of 2-(cyclohex-2-en-1-yl)-N-tosylacetamide ( 1a ) with (Z)-styryl bromides ( 2 ) gave cis-2-[(E)-styryl]cyclopent-3-en-1-yl-N-tosylacetamides in good to excellent yields. It is noticed that (Z)-styryl moiety was inverted into (E)-form in products. Unfortunately, (E)-styryl bromide substrates were not suitable for this reaction under the condition investigated. Further studies on norbornene system, we found that palladium-catalyzed reaction of endo-N-tosylbicyclo[2.2.1]hept-5-ene-2-carboxamide ( 6 ) with styryl bromides gave the Aza-Heck type products.