ChemInform Abstract: Unusual Pathway of the Tantalum‐Catalyzed Carboalumination Reaction of Alkenes with Triethylaluminum.

Abstract

Abstract Carboalumination of 1-alkenes (1-hexene, 1-octene, 1-decene) with Et 3 Al in the presence of catalytic amounts of TaCl 5 results in a mixture of 2-( R -substituted)- and 3-( R -substituted)- n -butylaluminums (1:1 ratio) in total yields of 75–85%. The TaCl 5 -catalyzed reaction of bicyclo[2.2.1]hept-2-ene, endo -tricyclo[5.2.1.0 2,6 ]deca-3,8-diene, and ( exo / endo )-5-methylbicyclo[2.1.1]hept-2-ene with Et 3 Al leads to the formation of diethyl[2- exo -(2′-norbornylethyl)]aluminums in high yields. DFT calculations confirm the thermodynamic preference of the final exo product. The multistep reaction mechanisms for the formation of the resultant organoaluminums through tantalacyclopentanes as key intermediates are also discussed.