Reactivity of Ortho-Palladated Phenol Derivatives with Unsaturated Molecules. 1. Insertion of CO, Isocyanides, Alkenes, and Alkynes. CO/Alkene, Alkyne/Isocyanide, and Isocyanide/Alkene Sequential Insertion Reactions^†

Reactions of HOC6H4I-2 with [Pd2(dba)3]·dba (“Pd(dba)2”; dba = dibenzylideneacetone) and N-donor ligands (4,4‘-di-tert-butyl-2,2‘-bipyridine (dtbbpy), N,N,N‘,N‘-tetramethylethylenediamine (tmeda), 1,10-phenanthroline (phen)) lead to the arylpalladium complexes [Pd(C6H4OH-2)I(L2)] (L2 = dtbbpy (1a‘), tmeda (1a‘ ‘), phen (1a‘ ‘‘)). Complexes 1a‘ and 1a‘ ‘ react with CO to give the aroyl derivatives [Pd{C(O)C6H4OH-2}I(dtbbpy)] (2a‘) and [Pd{C(O)C6H4OH-2}I(tmeda)] (2a‘ ‘), respectively. The compound 1a‘ reacts with isocyanides RNC (R = 2,6-dimethylphenyl (Xy), tBu) to give [Pd{C(NR)C6H4OH-2}I(dtbbpy)] (R = Xy (3a‘Xy), tBu (3a‘tBu)). The reactions of complexes [Pd(C6H4OX-2)I(bpy)] (X = H (1a), C(O)Me (1b)) and 1a‘ with alkynes RC⋮CR give the alkenyl complexes [Pd{CRCR(C6H4OX-2)}I(L2)] (X = H, R = CO2Me, L2 = bpy (4a), dtbbpy (4a‘); X = C(O)Me, L2 = bpy, R = CO2Me (4b), Ph (4b*)) through the insertion of the alkyne molecule into the palladium−carbon bond. When complex 1b reacts with PhC⋮CPh and TlOTf (1:3:1 molar ratio), the diinserted species [Pd{CPhCPh-CPhCPh(C6H4OC(O)Me-2)}(OTf)(bpy)] (5) is formed. Complexes 1a and 1a‘ insert 1,5-cyclooctadiene (C8H12) in the presence of TlOTf to give [Pd(η1(C):η2(C,C)-C8H12C6H4OH-2)(L2)]TfO (L2 = bpy (6a), dtbbpy (6a‘)). When similar reactions were carried out with 1a and 2,5-norbornadiene (C7H8), dicyclopentadiene (C10H12), or norbornene (C7H10), polyinserted species were obtained. The FAB+ mass spectra of these species give peaks for (M − OTf)+, where M = Pd{(C7H8)nC6H4OH-2}(bpy) (n = 1−10 or 1−18, depending on the amounts of diolefin used), Pd{(C10H12)nC6H4OH-2}(bpy) (n = 1−5), and [Pd{(C7H10)nC6H4OH-2}(OTf)(bpy)] (n = 1−11). The aroyl compound 2a reacts similarly with 2,5-norbornadiene or norbornene to give [Pd{(C7H8)nC(O)C6H4OH-2}(OTf)(bpy)] (n = 1−10) or [Pd{(C7H10)nC(O)(C6H4OH-2)}(OTf)(bpy)] (n = 1−10), respectively. The reaction of 4a with XyNC and TlOTf (1:1:1 molar ratio) gives [Pd{C(NXy)C(CO2Me)C(CO2Me)(C6H4OH-2)}(bpy)]TfO (7aXy), which is the result of the successive insertion of an alkyne and an isocyanide into a palladium−carbon bond. The reaction of 4a with a 4-fold excess of isocyanide gives dimethyl 2-(2,6-dimethylphenyl)imino-2H-chromene-3,4-dicarboxylate iminecoumarin (8), a result of the sequential insertion of alkyne and isonitrile into the Pd−C bond, followed by a depalladation process, as the only characterizable product. When 4b* reacts with XyNC and TlOTf [Pd{CPhCPh(C6H4OC(O)Me-2)}(CNXy)(bpy)]TfO (9b*Xy) is obtained. The compounds 3atBu, [Pd{C(NXy)(C6H4OC(O)Me-2)}I(bpy)] (3bXy), and [Pd{C(NXy)(C6H4CN-2)}I(bpy)] (3cXy) react with 2,5-norbornadiene or dicyclopentadiene in the presence of TlOTf to give the isocyanide/alkene inserted complexes [Pd{κ2C,N-(C7H8)C(NR)(C6H4X-2)}(bpy)]TfO (R = tBu, X = OH (10atBu); R = Xy, X = MeCO2 (10bXy), CN (10cXy)) or [Pd{κ2-C,N-(C10H12)C(NXy)(C6H4O2CMe-2)}(bpy)]TfO (10b*Xy), respectively. Other isocyanide/alkene sequentially inserted complexes can be obtained by reaction of trans-[Pd{C(NXy)(C6H4X-2)}I(CNXy)2] (X = OH (11aXy), CN (11cXy)) with 2,5-norbornadiene or norbornene and TlOTf, which renders cis-[Pd{κ2C,N-(C7H8)C(NXy)(C6H4X-2)}(CNXy)2]TfO (X = OH (12aXy), CN (12c‘Xy)) or cis-[Pd{κ2C,N-(C7H10)C(NXy)(C6H4OH-2)}(CNXy)2]TfO (12a*Xy), respectively. The crystal and molecular structures of 2a‘ ‘, 4a‘, 4b, 6a, 6a‘, 10atBu, 12aXy, and 12c‘Xy have been determined.邻碘苯酚（HOC₆H₄I-2）与三(二亚苄基丙酮)二钯(0)·二苄叉丙酮（[Pd₂(dba)₃]·dba，简称Pd(dba)₂；其中dba为二苄叉丙酮，dibenzylideneacetone），以及氮供体配体——4,4'-二叔丁基-2,2'-联吡啶（4,4'-di-tert-butyl-2,2'-bipyridine，dtbbpy）、N,N,N',N'-四甲基乙二胺（N,N,N',N'-tetramethylethylenediamine，tmeda）、1,10-菲啰啉（1,10-phenanthroline，phen）——发生反应，生成芳基钯配合物[Pd(C₆H₄OH-2)I(L₂)]（L₂分别为dtbbpy（1a'）、tmeda（1a''）、phen（1a'''））。 配合物1a'和1a''可与一氧化碳反应，分别得到酰基钯衍生物[Pd{C(O)C₆H₄OH-2}I(dtbbpy)]（2a'）与[Pd{C(O)C₆H₄OH-2}I(tmeda)]（2a''）。 配合物1a'与异氰化物RNC（R为2,6-二甲基苯基（Xy，二甲苯基）、叔丁基（tBu））反应，生成[Pd{C(=NR)C₆H₄OH-2}I(dtbbpy)]（R=Xy时为3a'_Xy，R=tBu时为3a'_tBu）。 配合物[Pd(C₆H₄OX-2)I(2,2'-联吡啶，bpy)]（X=H（1a）、C(O)Me（1b））与1a'分别与炔烃RC≡CR发生反应，通过炔烃分子插入钯-碳键，生成烯基钯配合物[Pd{CR=CR(C₆H₄OX-2)}I(L₂)]：X=H、R=CO₂Me、L₂=bpy（4a）、dtbbpy（4a'）；X=C(O)Me、L₂=bpy、R=CO₂Me（4b）、Ph（4b*）。 当配合物1b与二苯乙炔（PhC≡CPh）及三氟甲磺酸铊（TlOTf）以1:3:1的摩尔比反应时，生成双插入产物[Pd{CPh=CPh-CPh=CPh(C₆H₄OC(O)Me-2)}(OTf)(bpy)]（5），其中OTf为三氟甲磺酰氧基。 配合物1a与1a'可在三氟甲磺酸铊存在下，插入1,5-环辛二烯（C₈H₁₂），生成[Pd(η¹(C):η²(C,C)-C₈H₁₂C₆H₄OH-2)(L₂)]TfO（L₂=bpy（6a）、dtbbpy（6a'）），其中TfO为三氟甲磺酰氧基。 若以配合物1a分别与2,5-降冰片二烯（C₇H₈）、双环戊二烯（C₁₀H₁₂）或降冰片烯（C₇H₁₀）进行类似反应，则得到多插入产物。此类产物的快原子轰击正离子（FAB⁺）质谱中出现了(M − OTf)⁺的特征峰，其中M分别为Pd{(C₇H₈)ₙC₆H₄OH-2}(bpy)（n=1~10或1~18，具体数值取决于所用双烯烃的投料量）、Pd{(C₁₀H₁₂)ₙC₆H₄OH-2}(bpy)（n=1~5），以及[Pd{(C₇H₁₀)ₙC₆H₄OH-2}(OTf)(bpy)]（n=1~11）。 酰基配合物2a可与2,5-降冰片二烯或降冰片烯发生类似反应，分别得到[Pd{(C₇H₈)ₙC(O)C₆H₄OH-2}(OTf)(bpy)]（n=1~10）与[Pd{(C₇H₁₀)ₙC(O)(C₆H₄OH-2)}(OTf)(bpy)]（n=1~10）。 配合物4a与异氰化物XyNC及三氟甲磺酸铊以1:1:1的摩尔比反应，生成[Pd{C(=NXy)C(CO₂Me)=C(CO₂Me)(C₆H₄OH-2)}(bpy)]TfO（7a_Xy），该产物是炔烃与异氰化物依次插入钯-碳键的结果。 当配合物4a与4倍过量的异氰化物反应时，得到唯一可表征的产物——2-(2,6-二甲基苯基)亚氨基-2H-色烯-3,4-二羧酸二甲酯（又称亚胺基香豆素，8），该产物源于炔烃与异腈依次插入钯-碳键后，再发生脱钯反应。 当配合物4b*与XyNC及三氟甲磺酸铊反应时，得到[Pd{CPh=CPh(C₆H₄OC(O)Me-2)}(CNXy)(bpy)]TfO（9b*_Xy）。 配合物3a'_tBu、[Pd{C(=NXy)(C₆H₄OC(O)Me-2)}I(bpy)]（3b_Xy）以及[Pd{C(=NXy)(C₆H₄CN-2)}I(bpy)]（3c_Xy）可在三氟甲磺酸铊存在下，与2,5-降冰片二烯或双环戊二烯反应，生成异氰化物/烯烃依次插入的配合物：分别为[Pd{κ²C,N-(C₇H₈)C(=NR)(C₆H₄X-2)}(bpy)]TfO（R=tBu、X=OH（10a_tBu）；R=Xy、X=MeCO₂（10b_Xy）、CN（10c_Xy）），以及[Pd{κ²-C,N-(C₁₀H₁₂)C(=NXy)(C₆H₄O₂CMe-2)}(bpy)]TfO（10b*_Xy）。 其他异氰化物/烯烃依次插入的配合物可通过反式-[Pd{C(=NXy)(C₆H₄X-2)}I(CNXy)₂]（X=OH（11a_Xy）、CN（11c_Xy））与2,5-降冰片二烯或降冰片烯、三氟甲磺酸铊反应得到，产物分别为顺式-[Pd{κ²C,N-(C₇H₈)C(=NXy)(C₆H₄X-2)}(CNXy)₂]TfO（X=OH（12a_Xy）、CN（12c'_Xy）），以及顺式-[Pd{κ²C,N-(C₇H₁₀)C(=NXy)(C₆H₄OH-2)}(CNXy)₂]TfO（12a*_Xy）。 已测定配合物2a''、4a'、4b、6a、6a'、10a_tBu、12a_Xy及12c'_Xy的晶体与分子结构。