A tandem reaction is a reaction in which several bonds are formed in sequence without isolating intermediates. The tandem reaction below goes through three key reactions: a) a Suzuki-type coupling to generate 3, then b) deprotection of R₁ and installation of a triflate leaving group to generate 4, and finally c) a Heck-type coupling reaction to make 5. Using your knowledge of metal-catalyzed coupling reactions, please answer the following questions. OMe Pd(PPh3)4 (or PdL4) LOR₁ 1) TBAF (TBS deprotection) PdL₂ cat. 3 4 NaOEt, THF (solvent), 50 °C R₁ = TBS 2) TfO2, Et3N R₁ = Tf Et3N, THF 60 °C Br OMe 1 R₁ = TBS (alcohol protecting group) OH B HO 2 a) Draw the product 3 of the Suzuki-type coupling that occurs between 1 and 2. b) In 3, the R₁ group is TBS, a common protecting group for alcohols. Using tetrabutylammonium fluoride (TBAF), this TBS group can be removed to regenerate the alcohol. In a second step, a triflate leaving group (OTf) is installed at this position. These two steps produce 4 which is primed to participate in the final Heck reaction. Please draw 4.

Branch of chemistry concerned with the study of carbon-based compounds, also known as organic compounds. These compounds form due to carbon's notable potential in forming chemical bonds. Due to the abundance of organic compounds on Earth, organic chemistry is crucial in other scientific disciplines, including materials science and pharmaceutical science.