Catalytic Amphiphilic Allylation via Bis-π-allylpalladium Complexes and Its Application to the Synthesis of Medium-Sized Carbocycles

Abstract

The reaction of certain activated alkenes 3 with allyltributylstannane (4) and allyl chloride (5a) in the presence of palladium catalyst gave the bis-allylation products, 1,7-octadiene derivatives 6a−k, in good to high yields. The reaction of certain imines 9 with 4 and 5a under similar conditions as above afforded the bis-allylated amines, N-allyl-N-3-butene-1-amine derivatives 10a−f, in good to high yields. The bis-allylation reactions most probably proceed through bis-π-allylpalladium intermediate 2. The above intermolecular bis-allylation was extended to the intramolecular reaction. The reaction of 8-chloro-2,6-octadienyltributylstannane (17a) with activated alkenes 3 gave a mixture of regioisomeric cycloadducts, [8+2] and [4+2] cycloaddition products. The regioisomeric ratio was dependent on solvent and the electron density at the β-position of activated alkenes. In general, the [8+2] cycloadducts 18 were obtained predominantly in CH2Cl2, whereas the [4+2] adducts 24 and 25 were produced predominantly in DMF. The reaction of 7-chloro-2,8-nonadienyltributylstannane (17b) with activated alkenes gave selectively the [9+2] cycloadducts 19 and 22: the regioisomeric [5+2] and [7+2] adducts were not obtained at all. The reaction of 10-chloro-2,8-decadienyltributylstannane (17c) with activated alkene 3a afforded the [10+2] cycloadducts 20 and 23 in low yields. The mechanism on the intramolecular bis-allylation reaction is discussed.