Synthesis and Reactivity of <i>Ortho</i>-Mercuriated and <i>Ortho</i>-Palladated Arylacetals and Cyclic and Acyclic Aryldithioacetals. New Examples of the Rearrangement of Acyclic Dithioacetal Aryl- to Dithioether Alkyl-Palladium Complexes
作者:José Vicente、José-Antonio Abad、Francisco S. Hernández-Mata、Barbara Rink、Peter G. Jones、M. Carmen Ramírez de Arellano
DOI:10.1021/om0342964
日期:2004.3.1
The arylmercurial [HgC6H3(CHO)(2)-2,5}Cl] (1) reacts with CH(OMe)(3) or HS(CH2)(2)SH to give [HgC6H3CH(OMe)(2)}(2)-2,5}Cl] (2) or [Hg(Ar-a)Cl] [Ar-a = C6H3CH(SCH2CH2S)}(2)-2,5 (3a)], respectively. The mercurial 2 or 3a reacts with (NMe4)(2)[Pd2Cl6] and 2,2'-bipyridine (bpy) or with trans- [PdCl2(PPh3)(2)] to give the aryl-palladium complex [PdC6H3CH(OMe)(2)}(2)-2,5}Cl(bpy)] (4) or [Pd(kappa(2)-C,S-Ar-a)Cl(PPh3)] (5a*), respectively. The reaction of 1 with NaI3 renders IC6H3(CHO)(2)-2,5 (6), which reacts with HS(CH2)(2)SH to give IAra (7a). Similarly, IC6H(OMe)(3)-2,3,4-(CHO)-6 (8) reacts with HS(CH2)(2)SH or ToSH (To = C6H4Me-4) to give the corresponding dithioacetals IAX(b) [Ar-b = C6H(OMe)(3)-2,3,4-CH(SCH2CH2S)}-6 (7b)] or IC6H(OMe)(3)-2,3,4-CH(STo)(2)-6 (9). The iodoarene 7a or 7b adds oxidatively to "Pd(dba)(2)" (dba = dibenzylideneacetone) to give [Pd(kappa(2)-C, S-Ar)(mu-I)](2) [Ar = Ar-a (10a), Ar-b (10b)], which, in turn, reacts (i) with 1 equiv of PPh3 to give [Pd(kappa(2)-C,S-Ar)I(PPh3)] [Ar = Ar-a (5a), Ar-b (5b)], (ii) with Tl(TfO) (TfO = CF3SO3) and PPh3 (1:2:4 molar ratio) to give [Pd(kappa(2)-C, S-Ar-b)(PPh3)(2)]TfO (11b), or (iii) with 1 equiv of Tl(TfO) and bpy (1:2:2 molar ratio) to give [Pd(kappa(2)-C, S-Arb)(bpy)]TfO (11b*). Complexes 10 react with 1 equiv of isonitriles to give, after a short period of reaction, the complexes [Pd(kappa(2)-C,S-Ar)I(CNR)] [Ar = Ar-a, R = Xy = 2,6-dimethylphenyl (12a), Bu-t (12a'); Ar = Ar-b, R = Bu-t (12b')]. The iminoacyl complexes [Pd(kappa(2)-C,S-Im)(mu-I](2) [Im = Im(a) (13a), Im(b) (13b)] can be obtained by stirring a solution of 12a for 5 days to give 13a or by reacting 10b with XyNC in 1:1 molar ratio during 22 h to give 13b. Complexes 10 react with 2 equiv of isonitriles to give the iminoacyl complexes [Pd(kappa(2)-C,S-Im)l(CNR)] [Im = C(=NR)C6H3-CH(SCH2CH2S)}(2)-2,5, R = Xy, Im = Im(a) (14a), R = Bu-t, Im = Im(a')(14a'); Im = C(=NR)C6H(OMe)(3)-2,3,4-(SCH2CH2S)-6, R = Xy, Im = Im(b) (14b), R = Bu-t, Im = Im(b)' (14b')]. Complexes 14a,b react with 10a,b in 2:1 molar ratio to give 13a,b. Complexes 10a,b react with XyNC and Tl(TfO) (1:4:1) to give the dimeric cations [Pd(kappa(2)-C,S-Im)(CNXy)}(2)(mu-I)]TfO [R = Xy, Im = im(a) (15a), Im(b) (15b)].The compound [Pdkappa(2)-C,S-Ar-c}(mu-I)](2) (16) reacts (i) with PPh3 and Tl(TfO) in 1:4:2 molar ratio to give [Pd-II(kappa(2)-C,S-Ar-c)(PPh3)(2)]TfO <----> [Pd-0eta(2)-kappa(3)-C,S,S-S(To)=CHC6H(STo)-2-(OMe)(3)-3,4,5}(PPh3)(2)]TfO (17), (ii) with isonitriles in 1:2 or 1:4 molar ratio yielding complexes [Pd(kappa(2)-C,S-Ar-c)I(CNR)] [R = Xy (18), R = Bu-t (18')] or trans-[Pd(kappa(1)-C-Ar-c)I(CNR)(2)] [R = Xy (19), R = Bu-t (19')], respectively, and (iii) with PPh3 in 1:2 molar ratio yielding [Pd(kappa(2)-C,S-Ar-c)I(PPh3)] (20). The iodoarene 9 reacts with Pd(dba)(2) (i) and PPh3 (1:1:1 molar ratio) to give [Pdkappa(2)-C,S-Ar-c)I(PPh3)] [Ar-c = CH(STo)C6H(STo)-2-(OMe)(3)-3,4,5(20)] and (ii) PPh3 and Tl(TfO) (1: 1:2:1 molar ratio) to give 17. The crystal and molecular structures of 4, 5a*, 14a, and 14b have been determined by X-ray diffraction studies.