Question

Report Questions: What would you get as a product in Part A if cis-stilbene was used instead of the trans-stilbene? (Draw and think about the mechanism of the reactionl) Draw the proposed product with appropriate stereochemistry. Assign the chirality of the chiral centers. (Are these of the same absolute chirality when using trans-stilbene?) Is this a meso compound? Would this compound form the er same product as in Part B? Explain your answer.

conversion of stilbene to diphenylacetylene

Answer 1

Conversion of stilbene to diphenylacetylene

1. Br2 2. Base, A trans - stillbene Cliphenyl acetylene Alhongh the first step could be accomplished by Using, elemental bromine which is a red liquid that is highly "Corrosive and is a Tachrymator , you are going to generate your bromine in silu (in The reaction mixture) Ubing à Solid reagent, pyridinium hy drobromide perbromide. This reagent generates the bromine for the reaction via the following equtlibrium Pyridinium hydrobromide perbromide when the vicinal dihalide formed from the addition reaction is heated with a strong base in a Br, — Br + Bra Z - I

High boiling Solvent, two equivalents of HBr are eliminated generating the Alkyne functional group 1. Br H KOH Нос, Сң оң H BY