Let's solve each reaction step by step. All of these reactions involve the **Stille coupling**, a palladium-catalyzed cross-coupling between an organostannane (R-SnBu₃) and an organohalide (R'-X). --- ## **1. First Reaction** ### **Given:** - **Reactants:** - (TMS-alkene)-SnBu₃ - Bromocyclopentadiene - **Catalyst:** Pd(PPh₃)₄, toluene, 80°C ### **Step-by-Step Solution:** 1. **Identify Stille Coupling:** The organostannane (R-SnBu₃) reacts with the aryl/vinyl halide (R'-Br) in the presence of Pd() catalyst. 2. **Coupling:** The SnBu₃ group is replaced by the aryl/vinyl group from the halide, forming a new C–C bond. ### **Product:** - The double bond (alkene) with the TMS group is now attached to the cyclopentadiene ring (where Br was). - Final product: ``` (TMS-alkene)-cyclopentadiene ``` --- ## **2. Second Reaction** ### **Given:** - **Step 1:** p-Tolyl lithium + Bu₃SnCl → p-Tolyl-SnBu₃ - **Step 2:** p-Tolyl-SnBu₃ + 2-bromo-4-fluoropyrrole (Pd catalyst) ### **Step-by-Step Solution:** 1. **Transmetallation:** The p-tolyl lithium reacts with Bu₃SnCl to give p-tolyl-SnBu₃. 2. **Stille Coupling:** This organostannane reacts with bromo-fluoropyrrole, attaching the p-tolyl group to the pyrrole where Br was. ### **Product:** - p-Tolyl attached to pyrrole at the 2-position (where Br was), with F still at the 4-position. --- ## **3. Third Reaction** ### **Given:** - **Reactant:** A molecule with both Br and SnBu₃ groups, plus a fused ring system (decalin derivative). - **Catalyst:** Pd(PPh₃)₄, toluene ### **Step-by-Step Solution:** 1. **Intramolecular Stille Coupling:** The Br and SnBu₃ are on the same molecule. Under Pd() catalysis, they form a new C–C bond, closing a ring. ### **Product:** - A new fused ring is formed, connecting the carbons originally bearing Br and SnBu₃. --- ## **Summary Table** | Step | Type of Reaction | Main Transformation | Product Sketch | |------|---------------------|------------------------------------------|---------------------------------------------------------------------| | 1 | Stille Coupling | Attach TMS-alkene to cyclopentadiene |  | | 2 | Stille Coupling | Attach p-tolyl to 2-position of pyrrole |  | | 3 | Intramolecular Stille | Form new ring (close the molecule) |  | --- ## **Final Answers (in words):** ### 1. **(TMS-alkene)-cyclopentadiene** The alkene chain with a TMS group is attached to cyclopentadiene at the position where Br was. ### 2. **p-Tolyl-2-fluoropyrrole** The p-tolyl group is attached to the 2-position of the pyrrole ring (where Br was), F remains at the 4-position. ### 3. **Fused bicyclic ring** The molecule forms a new C–C bond between the formerly bromo and stannyl groups, resulting in a fused bicyclic system. --- **If you need the explicit structures drawn out, let me know!**