Syntheses of palladated aryldithioacetals. Unexpected rearrangement involving C-S and C-Pd bonds

The reaction of C6HI(OMe)(3)-2,3,4-CH(STo)(2)-6 (1) (To = 4-tolyl) with [Pd (dba)(2)] (dba = dibezylideneacetone) at room temperature gives [Pd-2{kappa (2)-C, S-CH(STo)(C6H(STO-2)(OMe)(3-)3,4,5)(2)(mu -I)(2)] (3) or, in the pr esence of TI(OTf) (OTf = CF3SO3) and bpy (2,2'-bipyridine), the cationic cy clopalladated complex [Pd{kappa (2)-C, S-C6H(OMe)(3)-2,3,4-CH(STo)(2)-6}(bp y)]OTf (2). 3 reacts with Tl(OTf) and (i) RNC (1:2:4) to give cis- [Pd{kapp a (2)-C,S-CH(STo)}{C6H(STo-2)(OMe)(3)-3,4,5} S(CNR)(2)] OTf [R = 2,6-dimeth ylphenyl (4), Bu-t (4')] or (ii) bpy to give an isomeric form of 2, cis- [P d(kappa (2)-C,S-CH(STo){C6H(STo-2)(OMe)(3)-3,4,5}}(bpy)]OTf (5). The last r eaction can be reversed by reacting 5 with NaI. The compound 2 reacts with NaI to give [Pd(C6H(OMe)(3)-2,3,4-CH(STo)(3)-6))(bpy)] (6), which can be al so prepared by reaction of 1 with [Pd(dba)(2)] in the presence of bpy. Comp lex 2 isomerizes to 5 when refluxed in 1,2-dichloroethane. The crystal stru ctures of 2 and 4 have been determined by X-ray diffraction studies.