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<sup>⊥</sup>

The arylmercurial [Hg{C<sub>6</sub>H<sub>3</sub>(CHO)<sub>2</sub>-2,5}Cl] (<b>1</b>) reacts with CH(OMe)<sub>3</sub> or HS(CH<sub>2</sub>)<sub>2</sub>SH to give [Hg{C<sub>6</sub>H<sub>3</sub>{CH(OMe)<sub>2</sub>}<sub>2</sub>-2,5}Cl] (<b>2</b>) or [Hg(Ar<sub>a</sub>)Cl] [Ar<sub>a</sub> = C<sub>6</sub>H<sub>3</sub>{CH(SCH<sub>2</sub>CH<sub>2</sub>S)}<sub>2</sub>-2,5 (<b>3a</b>)], respectively. The mercurial <b>2</b> or <b>3a</b> reacts with (NMe<sub>4</sub>)<sub>2</sub>[Pd<sub>2</sub>Cl<sub>6</sub>] and 2,2‘-bipyridine (bpy) or with <i>trans</i>-[PdCl<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] to give the aryl-palladium complex [Pd{C<sub>6</sub>H<sub>3</sub>{CH(OMe)<sub>2</sub>}<sub>2</sub>-2,5}Cl(bpy)] (<b>4</b>) or [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar<sub>a</sub>)Cl(PPh<sub>3</sub>)] (<b>5a*</b>), respectively. The reaction of <b>1</b> with NaI<sub>3</sub> renders IC<sub>6</sub>H<sub>3</sub>(CHO)<sub>2</sub>-2,5 (<b>6</b>), which reacts with HS(CH<sub>2</sub>)<sub>2</sub>SH to give IAr<sub>a</sub> (<b>7a</b>). Similarly, IC<sub>6</sub>H(OMe)<sub>3</sub>-2,3,4-(CHO)-6 (<b>8</b>) reacts with HS(CH<sub>2</sub>)<sub>2</sub>SH or ToSH (To = C<sub>6</sub>H<sub>4</sub>Me-4) to give the corresponding dithioacetals IAr<sub>b</sub> [Ar<sub>b</sub> = C<sub>6</sub>H(OMe)<sub>3</sub>-2,3,4-{CH(SCH<sub>2</sub>CH<sub>2</sub>S)}-6 (<b>7b</b>)] or IC<sub>6</sub>H(OMe)<sub>3</sub>-2,3,4-CH(STo)<sub>2</sub>-6 (<b>9</b>). The iodoarene <b>7a</b> or <b>7b </b>adds oxidatively to “Pd(dba)<sub>2</sub>” (dba = dibenzylideneacetone) to give [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar)(μ-I)]<sub>2</sub> [Ar = Ar<sub>a</sub> (<b>10a</b>), Ar<sub>b</sub> (<b>10b</b>)], which, in turn, reacts (i) with 1 equiv of PPh<sub>3</sub> to give [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar)I(PPh<sub>3</sub>)] [Ar = Ar<sub>a</sub> (<b>5a</b>), Ar<sub>b</sub> (<b>5b</b>)], (ii) with Tl(TfO) (TfO = CF<sub>3</sub>SO<sub>3</sub>) and PPh<sub>3</sub> (1:2:4 molar ratio) to give [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar<sub>b</sub>)(PPh<sub>3</sub>)<sub>2</sub>]TfO (<b>11b</b>), or (iii) with 1 equiv of Tl(TfO) and bpy (1:2:2 molar ratio) to give [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar<sub>b</sub>)(bpy)]TfO (<b>11b*</b>). Complexes <b>10</b> react with 1 equiv of isonitriles to give, after a short period of reaction, the complexes [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar)I(CNR)] [Ar = Ar<sub>a</sub>, R = Xy = 2,6-dimethylphenyl (<b>12a</b>), <sup>t</sup>Bu (<b>12a</b>‘); Ar = Ar<sub>b</sub>, R = <sup>t</sup>Bu (<b>12b</b>‘)]. The iminoacyl complexes [Pd(<i>κ</i><i><sup>2</sup></i><sup></sup>-<i>C,S</i>-Im)(μ-I)]<sub>2</sub> [Im = Im<sub>a</sub> (<b>13a</b>), Im<sub>b</sub> (<b>13b</b>)] can be obtained by stirring a solution of <b>12a</b> for 5 days to give <b>13a</b> or by reacting <b>10b</b> with XyNC in 1:1 molar ratio during 22 h to give <b>13b</b>. Complexes <b>10</b> react with 2 equiv of isonitriles to give the iminoacyl complexes [Pd(κ<sup>2</sup>-<i>C,S</i>-Im)I(CNR)] [Im = C(NR)C<sub>6</sub>H<sub>3</sub>{CH(SCH<sub>2</sub>CH<sub>2</sub>S)}<sub>2</sub>-2,5, R = Xy, Im = Im<sub>a</sub> (<b>14a</b>), R = <sup>t</sup>Bu, Im = Im<sub>a</sub><sub>‘</sub> (<b>14a</b>‘); Im = C(NR)C<sub>6</sub>H(OMe)<sub>3</sub>-2,3,4-(SCH<sub>2</sub>CH<sub>2</sub>S)-6, R = Xy, Im = Im<sub>b</sub> (<b>14b</b>), R = <sup>t</sup>Bu, Im = Im<sub>b</sub><sub>‘</sub> (<b>14b</b>‘)]. Complexes <b>14a</b>,<b>b</b> react with <b>10a</b>,<b>b</b> in 2:1 molar ratio to give <b>13a</b>,<b>b</b>. Complexes <b>10a</b>,<b>b</b> react with XyNC and Tl(TfO) (1:4:1) to give the dimeric cations [Pd{(<i>κ</i><sup>2</sup>-<i>C,S</i>-Im)(CNXy)}<sub>2</sub>(μ-I)]TfO [R = Xy, Im = Im<sub>a</sub> (<b>15a</b>), Im<sub>b</sub> (<b>15b</b>)]. The compound [Pd{<i>κ</i><sup>2</sup>-<i>C,S</i>-Ar<sub>c</sub>}(μ-I)]<sub>2</sub> (<b>16</b>) reacts (i) with PPh<sub>3</sub> and Tl(TfO) in 1:4:2 molar ratio to give [Pd<sup>II</sup>(<i>κ</i><sup>2</sup>-<i>C,S</i>-Ar<sub>c</sub>)(PPh<sub>3</sub>)<sub>2</sub>]TfO ↔ [Pd<sup>0</sup>{η<i><sup>2</sup></i><sup></sup>-κ<sup>3</sup>-<i>C,S,S</i>-<i>S</i>(To)<i>C</i>HC<sub>6</sub>H(STo)-2-(OMe)<sub>3</sub>-3,4,5}(PPh<sub>3</sub>)<sub>2</sub>]TfO (<b>17</b>), (ii) with isonitriles in 1:2 or 1:4 molar ratio yielding complexes [Pd(<i>κ</i><sup>2</sup>-<i>C,S</i>-Ar<sub>c</sub>)I(CNR)] [R = Xy (<b>18</b>), R = <sup>t</sup>Bu (<b>18</b>‘)] or <i>trans</i>-[Pd(<i>κ</i><sup>1</sup><i>-C</i>-Ar<sub>c</sub>)I(CNR)<sub>2</sub>] [R = Xy (<b>19</b>), R = <sup>t</sup>Bu (<b>19</b>‘)], respectively, and (iii) with PPh<sub>3</sub> in 1:2 molar ratio yielding [Pd(κ<sup>2</sup>-<i>C,S</i>-Ar<sub>c</sub>)I(PPh<sub>3</sub>)] (<b>20</b>). The iodoarene <b>9</b> reacts with Pd(dba)<sub>2</sub> (i) and PPh<sub>3</sub> (1:1:1 molar ratio) to give [Pd{<i>κ</i><sup>2</sup>-<i>C,S</i>-Ar<sub>c</sub>)I(PPh<sub>3</sub>)] [Ar<sub>c</sub> = CH(STo)C<sub>6</sub>H(STo)-2- (OMe)<sub>3</sub>-3,4,5 (<b>20</b>)] and (ii) PPh<sub>3</sub> and Tl(TfO) (1:1:2:1 molar ratio) to give <b>17</b>. The crystal and molecular structures of <b>4</b>, <b>5a*</b>, <b>14a</b>, and <b>14b </b>have been determined by X-ray diffraction studies.