10. Addition Reactions

Cyclopropanation using any of the reagents discussed here is stereospecific.

(b) Draw a reaction coordinate diagram for cyclopropanation.

Propose mechanisms consistent with the following reactions.

(d)

Predict the product of the following reactions.

(a)

Dichlorocarbene can also be generated by heating sodium trichloroacetate. Propose a mechanism for the reaction.

Show how you would synthesize each compound using methylenecyclohexane as your starting material.

(g)

Cyclopropanation using any of the reagents discussed here is stereospecific.

(a) What does this say about the mechanism?

Limonene is one of the compounds that give lemons their tangy odor. Show the structures of the products expected when limonene reacts with an excess of each of these reagents.

m. CHBr₃ and 50% aq. NaOH

Suggest a mechanism for the reaction shown in Figure 16.30 using IZnCH₂I as the cyclopropanating reagent.

In addition to radicals, anions, and cations, a fourth class of reactive intermediates is carbenes. A neutral species, the simplest carbene has a molecular formula of CH₂.

(h) Of the reactions studied here in Chapter 8, cyclopropanation is most similar to which?

Predict the carbenoid addition products of the following reactions.

(a) cyclohexene + CHCl₃, 50% NaOH/H₂O

In addition to radicals, anions, and cations, a fourth class of reactive intermediates is carbenes. A neutral species, the simplest carbene has a molecular formula of CH₂ .

(e) Carbenes have great synthetic utility, especially in the synthesis of cyclopropanes from alkenes. Based on your answers to (a)–(d), show a mechanism for the cyclopropanation of cyclohexene.

Show how you would accomplish each of the following synthetic conversions. 

a. trans-but-2-ene → trans-1,2-dimethylcyclopropane

When dichloromethane is treated with strong NaOH, an intermediate is generated that reacts like a carbene. Draw the structure of this reactive intermediate, and propose a mechanism for its formation.