Nucleophilic Addition Reactions of Tricarbonyl [η⁵‐1‐(Phenylthio)Cyclohexadienyl]Iron(I) Complex

Abstract

Hydride abstraction of tricarbonylln'vl-tphenylthio)-t ,3-cycIobexadiene]iron(O) complex 2 with Ph 3C+PF6 -regiospecifically provided the title compound 3 in excellent yield. Cationic complex 3 could react with a variety of nucleophiles in good yield. Hard nucleophiles prefer to attack at the C-I position, whereas soft and hindered nucleophiles favor attack at the C-S position. Some synthetic applications were also studied, S-dienylium complex 3 in excellent yield (Eq. 0, which was characterized by 'n and BC NMR spectroscopy and analytical methods.The reactions of 3 with a rangeof nucleophiles (Eq, 2) are shown in Table 1. It can be seen that heteroatom nucleophiles (entries 1-3) reacted smoothly with 3 at C-S to give the T)4-iron complexes 4. The cyanide anion (entry 4), however, gave a mixture of C-5 and C-1 addition products 4d and 5d, respectively. The regiochemistry of 4d and 5d have been assigned based on the III NMR and DEPT experiments. Compound 4d has two protons at 0 6.13 (d, J =4.2 Hz, H-2) and 0 5.43 (dd, J =4.2, 6.4 Hz, H-3), and one quarternary carbon at 0 72.8 (C-l), whereas compound 5d has two protons at 05.50 (dd, J = 4.8, 6.3 Hz, H-3) and 05.40 (dd, J = 4.5, 4.8 Hz, H-4) and a quarternary carbon at 0 43.4