Mechanism of Aryldestannylation of Alkenylstannanes with Arylpalladium Complexes

• Project/Area Number: 02640413
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 有機化学一般
• Research Institution: Kinki University
• Principal Investigator: KIKUKAWA Kiyoshi Kinki University in Kyushu, Faculty of Engineering, Department of Industrial Chemistry, Professor, 工学部・工業化学科, 教授 (60037918)
• Project Period (FY): 1990 – 1991
• Project Status: Completed (Fiscal Year 1991)
• Budget Amount: ¥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)
• Keywords: Alkenylstannanes / Organotins / Organopalladium / Homogeneous Catalyst / Transmetallation / C-C Coupling / Arylation / Electrophilic Substitution

Research Abstract

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.
<<chemical formula>>
In the absence of coordinatively strong ligands, the reaction with [Ar-Pd]^+BF_4^- proceeds through addition-elimination mechanism as following scheme.
<<chemical formula>>
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.