(.pi.-Allyl)palladium complexes of norcamphene. Structure and reactivity

Evidence of Formation of anexo-π-Allyl Complex Intermediate in the Pd0-Catalyzed Alkylation of a Bicyclic Allylic Diacetate with Stabilized Carbon Nucleophiles

“…Possible isomerization pathways for the interconversion of complexes I and II s(phenylsulfonyl)methane. Moreover, isolation of compound 7 in 79% yield and its subsequent treatment with NaH or BSA/KOAc in presence of a catalytic amount of Pd(PPh 3 ) 4 did not afford any other product.…”

“…of sodium bis(methoxycarbonyl)methanide in THF in the presence of 1.5 mol-% of Pd(PPh 3 ) 4 at room temperature, afforded after 5 min, comScheme 2. Pd 0 -catalyzed alkylation of bicyclic diacetate 1 with sodium bis(methoxycarbonyl)methanide 65°C/32 h [a] Small amounts of 5a and 5b were also formed.…”

“…[13] We further found that 8 can also be obtained in 68% yield by simple reaction of 1 with 1 equivalent of Scheme 5. Pd 0 -catalyzed alkylation of bicyclic diacetate 1 with triphenylphosphane triphenylphosphane in the presence of 1.5 mol-% of Pd(PPh 3 ) 4 at room temperature for 32 h (Scheme 5).…”

“…General Procedure for the Palladium-Catalyzed Alkylation of 1 with Sodium Bis(methoxycarbonyl)methanide: To a solution of Pd(PPh 3 ) 4 (0.350 g; 0.3 mmol) in THF (5 mL) was added a solution of 1 [5] (2.36 g, 10 mmol) in THF (5 mL) under a nitrogen atmosphere. After stirring for 5 min.…”

“…Petit [3] and Godleski [4] were the first to provide evidence for an exo-(π-allyl)palladium dimeric complex, derived from norcamphene, by X-ray structure analysis that is in direct accordance with its reactivity towards the hydride nucleophile. Recently, we have described the synthesis of a new prochiral bicyclic diacetate, namely 2,3-bis(acetoxymethyl)bicyclo[2.2.1]hepta-2,5-diene 1, and its use in palladium(0)-catalyzed elimination to produce compound 2.…”