Heck reaction group-selective

It has been proven that palladium catalyzed reductive Heck reactions are versatile and high-yield approach for preparing of new bioactive alkaloid epibatidine (1) analognes fromN-benzoylated 2-aza-bicyclo[2.2.1]hept-5-ene (3) and it has been shown that in case of aryl- groups reaction progresses regioselectively. All Heck type reactions proceed exo-selectively, leading to the same stereochemistry as fonnd in 1. 

With the spirocycle in hand, a regioselective and stereoselective Heck reaction was used to install the substituted aromatic portion of the molecule (Scheme 28.5). It is interesting that the addition of water to the reaction provided the high selectivity. The remaining olefin was reduced over Pearlman s catalyst, and the protecting groups were removed to provide the desired NK-1 antagonist 14 in 7 overall steps.33... 

Shibasaki s first group-selective Heck reaction... 

Scheme 6-32 Group-selective asymmetric Heck reactions.

Macromolecular metal complexes of soluble dendrimers with catalytically active groups on their surface have been used in hydrogenation [112, 113], Kharasch addition [114], Heck reactions and hydroformylation [115-118], metathesis of unsaturated compounds [119-121], oxidation [122], etc. The use of dendrimers in most cases enabled catalyst reuse and also influenced the activity and selectivity of the processes. 

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