91Ó°ÊÓ

Draw the product of each coupling reaction.

a.

b.

c.

d.

What reagents are needed to convert 2-methylpropene $[\left({\mathrm{CH}}_3\right)C={\mathrm{CH}}_2]$to each compound? More than one step may be required.

a.

b.

c.

What product is formed when each alkene is treated with and Zn(Cu)?

a.

b.

c.

What stereoisomers are formed when trans-hex-3-ene is treated with$\mathit{C}{\mathit{H}}_{\mathbf{2}}{\mathbf{I}}_{\mathbf{2}}$ and Zn(Cu)?

Draw the products formed when each alkene is treated with Grubbs catalyst.

a.

b.

c.

What products are formed when cis-pent-2-ene undergoes metathesis? Use this reaction to explain why metathesis of a 1, 2-disubstituted alkene $\left(\mathrm{RCH}=\mathrm{CHR}\text{'}\right)$ is generally not a practical method for alkene synthesis?

Draw the product formed from ring-closing metathesis of each compound.

a.

b.

What product is formed by ring-closing metathesis of compound V, a key intermediate in the synthesis of ingenol, a natural product mentioned in the chapter opener?

What starting material is needed to synthesize each compound by a ring-closing metathesis reaction?

a.

b.

c.

In addition to organic halides, alkyl tosylates (R'OTs, Section 9.13) also react with organocuprates ( ${\mathbf{R}}_{\mathbf{2}}\mathbf{CuLi}$) to form coupling products R-R'. When 2° alkyl tosylates are used as starting materials ( ${\mathbf{R}}_{\mathbf{2}}\mathbf{CHOTs}$), inversion of the configuration at a stereogenic center results. Keeping this in mind, draw the product formed when each compound is treated with ${\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}\mathbf{CuLi}$.

a.

b.