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), t Bu) to give [Pd{C(NR)C6H4OH-2}I(dtbbpy)] (R = Xy (3a‘Xy), t Bu (3a‘ t Bu)). 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) n C6H4OH-2}(bpy) (n = 1−10 or 1−18, depending on the amounts of diolefin used), Pd{(C10H12) n C6H4OH-2}(bpy) (n = 1−5), and [Pd{(C7H10) n C6H4OH-2}(OTf)(bpy)] (n = 1−11). The aroyl compound 2a reacts similarly with 2,5-norbornadiene or norbornene to give [Pd{(C7H8) n C(O)C6H4OH-2}(OTf)(bpy)] (n = 1−10) or [Pd{(C7H10) n C(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 3a t Bu, [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{κ 2 C,N-(C7H8)C(NR)(C6H4X-2)}(bpy)]TfO (R = t Bu, X = OH (10a t Bu); R = Xy, X = MeCO2 (10bXy), CN (10cXy)) or [Pd{κ 2 -C,N-(C10H12)C(NXy)(C6H4O2CMe-2)}(bpy)]TfO (10b*Xy), respectively. Other isocyanide/alkene sequentially ...

Helpful neighbors: [Pd{2‐(OH)C6H4}I(tmeda)] reacts at room temperature with excess RCN (R=Me, C6F5, CH2CH) and TlOTf (1 equiv) to give [Pd{1‐O‐2‐[C(R)NH]C6H4‐κ2‐O,N}(tmeda)]OTf (see scheme). The proximal OH group plays a crucial role in this first example of the insertion of a nitrile into a late‐transition‐metal–carbon bond. Tf=trifluoromethanesulfonyl, tmeda=N,N,N′,N′‐ tetramethylethylenediamine.

The first examples of the insertion of carbodiimides into a late-transition-metal−carbon bond and the unprecedented intramolecular addition of a phenol to a carbodiimide have allowed the synthesis of O,N and O,C six-membered palladacycles.

Complexes [Pd(C(6)H(3)XH-2-R'-5)Y(N;N)] (X=O, NH; Y=Br, I; R'=H, NO(2); N;N=N,N,N',N'-tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bpy), 4,4'-di-tert-butyl-2,2'-bipyridine (dtbbpy)) react with RN=C=E (E=NR, S) or RC identical withN (R=alkyl, aryl, NR''(2)) and TlOTf (OTf=CF(3)SO(3)) to give, respectively, 1) products of the insertion of the C=E group into the C--Pd bond, protonation of the N atom, and coordination of X to Pd, [Pd{kappa(2)-X,E-(XC(6)H(3){EC(NHR)}-2-R'-4)}(N;N)]OTf or [Pd(kappa(2)-X,N-{ZC(6)H(3)(NH=CR)-2-R'-4})(N;N)]OTf, or products of the coordination of carbodiimides and OH addition, [Pd{kappa(2)-C,N-(C(6)H(4){OC(NR)}NHR-2)}(bpy)]OTf; or 2) products of the insertion of the C identical withN group to Pd and N-protonation, [Pd(kappa(2)-X,N-{XC(6)H(3)(NH=CR)-2-R'-4})(N;N)]OTf.

Dimethyl maleate and dimethyl and diethyl fumarates (RO2CCHCHCO2R) have been reacted with [Pd(C6H4Ro-2)Y(N∧N)] (Ro = OH, CHO, CN, Y = Br, I, N∧N = tmeda, bpy, dtbbpy; 1:1:4.5 molar ratio) and TlOTf to afford complexes resulting from the stereoselective insertion of the olefin and coordnation to Pd of one carbonyl oxygen, giving an enantiomeric mixture of the five-membered metallacyclic complexes [Pd{κ2 C,O-2-[CH(CO2R)CHCO2R]C6H4Ro}(N∧N)]OTf (R = Me, Et). From dimethyl maleate, the isolated complexes were RR/SS mixtures with Ro = OH, N∧N = tmeda (2aOH), dtbbpy (2cOH) and N∧N = bpy, Ro = CHO (2bCHO), CN (2bCN) and from the fumarates RS/SR mixtures with N∧N = bpy, Ro = CHO, R = Me (3bCHO), Et (4bCHO). Complex 2bCHO reacts with RNC in a 1:1 or 1:3 molar ratio to give the complexes [Pd{2-[CH(CO2R)CHCO2R]C6H4CHO}}(CNR′) n (bpy)3−n ]OTf (R = Me, n = 1, R′ = Xy (5bCHO), tBu = (6bCHO); n = 3, R = Xy (7bCHO), tBu = (8bCHO)). Similarly, the fumarate derivative 3bCHO or 4bCHO afforded the corresponding complexes where R = Me, n = 1, R′ = Xy (9bCHO), n = 3, R′ = tBu (10bCHO) or R = Et, n = 3, R′ = Xy (11bCHO), tBu (12bCHO), respectively. 1,1-Dimethylallene reacts with [Pd(C6H4OH-2)I(N∧N)] to give the η3-allyl complexes [Pd{η3-CH2C(C6H4OH-2)CMe2}(N∧N)]OTf (N∧N = tmeda (13aOH), dtbbpy (13cOH)). The crystal structures of 2aOH, 4bCHO, 7bCHO, and 13aOH have been determined.