91Ó°ÊÓ

Question: What alkenes are formed when each alcohol is dehydrated with TsOH? Label the major product when a mixture results.

a.

b.

c.

d.

Question: Draw the products formed when ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{OTs}$is treated with each reagent.

$$\begin{gathered} \mathbf{a}\mathbf{.}\mathbf{}{\mathbf{CH}}_{\mathbf{3}}\mathbf{SH} \\ \mathbf{b}\mathbf{.}\mathbf{}{\mathbf{NaOCH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{3}} \\ \mathbf{c}\mathbf{.}\mathbf{}\mathbf{NaOH} \\ \mathbf{d}\mathbf{.}\mathbf{}\mathbf{KOC}{\left({\mathrm{CH}}_3\right)}_{\mathbf{3}} \end{gathered}$$

Question: Draw the products of each reaction and indicate stereochemistry around stereogeniccenters.

a.

b.

c.

d.

Question: Draw the product of the following reaction, one step in the synthesis of the antiplatelet agent clopidogrel used to reduce the risk of stokes.

Question: Name each epoxide.

a.

b.

c.

Question: Draw the substitution product formed (including stereochemistry) when (R)-hexan-2-ol is treated with each series of reagents: (a) NaH, followed by ${\mathbf{CH}}_{\mathbf{3}}\mathbf{I}$ ; (b) TsCl and pyridine, followed by ${\mathbf{NaOCH}}_{\mathbf{3}}$ ; (c) ${\mathbf{PBr}}_{\mathbf{3}}$, followed by ${\mathbf{NaOCH}}_{\mathbf{3}}$. Which two routes produce identical products?

Question: a) What is the major alkene formed when A is dehydrated with ${\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$ ? (b) What is the major alkene formed when A is treated with ${\mathbf{POCl}}_{\mathbf{3}}$and pyridine? Explain why the major product is different in these reactions.

Question: Draw a stepwise mechanism for the following reaction.

Question: Although alcohol V gives a single alkene W when treated with POCl₃ and pyridine, three isomeric alkenes (X–Z) are formed on dehydration with H₂SO₄. Draw a stepwise mechanism for each reaction and explain why the difference occurs.

Question: Sometimes carbocation rearrangements can change the size of a ring. Draw a stepwise, detailed mechanism for the following reaction.