Mechanism of Aryldestannylation of Alkenylstannanes with Arylpalladium Complexes

ArPd（PPh_3）_2I和ArPd（PPh_3）_2BF_4分别与PhCH=CHSnR_3和Ph（R_3Sn）C=CH_2（R=Bu，Ph）芳基脱锡，得到PhCH=CHAr和Ph（Ar）C=CH_2。在没有强中性配体如PPh@_3存在下，钯配合物的反阴离子对反应曲线有明显的影响。在强配位配体PPh_3或I ~（^-）存在下，芳基钯与烯基锡烷通过金属转移-还原消除反应生成芳基脱锡基锡烷。在<chemical formula>没有强配位的配体存在下，[Ar-Pd]^+BF_4^-的反应是通过加成-消除机理进行的。在<chemical formula>钯催化的有机亲电试剂与有机金属化合物的C-C偶联反应中，有机钯物种有望成为关键中间体。研究结果表明，有机钯中间体的配体在设计反应途径中具有重要作用。

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.