|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1991 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1990 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Both ArPd(PPh_3)_2I and ArPd(PPh_3)_2BF_4 aryldestannylated PhCH=CHSnR_3 and Ph(R_3Sn)C=CH_2(R=Bu, Ph)to give PhCH=CHAr and Ph(Ar)C=CH_2, respectively. In the absence of strong neutral ligands such as PPh@_3, however, the counter anion of the palladum complexes showed drastic effect on the reaction profile. Reaction with PhCH=CHSnR_3, [ArPd]^+BF_4^- gave Ph(Ar)C=CH_2, whereas Ar-Pd-I gave PhCH=CHAr.
In the presence of coordinatively strong ligands such as PPh_3 or I^-, arylpalladium complexes aryldestannylate alkenylstannanes via transmetallation-reductive elimination mechanism as following scheme.
In the absence of coordinatively strong ligands, the reaction with [Ar-Pd]^+BF_4^- proceeds through addition-elimination mechanism as following scheme.
In the palladium catalyzed C-C coupling of organic electrophiles with organometallics, organs-palladium species expect to be a key intermediate. Present results exemplify an important role of the ligands of organopalladium intermediates to design reaction pathway.