10. Addition Reactions

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

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.

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

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

(b)

Predict the carbenoid addition products of the following reactions.

(b)

Predict the carbenoid addition products of the following reactions.

a. trans-hex-3-ene + CH₂I₂, Zn(Cu)

b. cis-hex-3-ene + CH₂I₂, Zn(Cu)

Predict the carbenoid addition products of the following reactions.

(c)

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.

Provide an arrow-pushing mechanism for the cyclopropanation of cyclohexene with methylene carbene. Rationalize the outcome.

Cyclopropanation using any of the reagents discussed here is stereospecific.

(a) What does this say about the mechanism?

Predict the product of the following reactions.

(b)