14. Synthetic Techniques

Supply the reagents necessary to accomplish the following transformation.

Propose a synthesis

Supply the reagents necessary to accomplish the following transformation.

Compound A (C7H11Br) is treated with magnesium in ether to give B (C7H11MgBr), which reacts violently with D2O to give 1-methylcyclohexene with a deuterium atom on the methyl group (C). Reaction of B with acetone (CH3COCH3) followed by hydrolysis gives D (C10H18O). Heating D with concentrated H2SO4 gives E (C10H16), which decolorizes two equivalents of Br2 to give F (C10H16Br4). E undergoes hydrogenation with excess H2 and a Pt catalyst to give isobutylcyclohexane. Determine the structures of compounds A through F, and show your reasoning throughout.

Show how you would convert the following starting materials into the target compound.

You may use any additional reagents you need.

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Using any necessary inorganic reagents,

show how you would convert acetylene and isobutyl bromide to

(b) (±)-2,7-dimethyloctane-4,5-diol.

Beginning with the molecules on the left of each chemical equation, synthesize the molecules shown. While there can be multiple ways of doing each synthesis, the minimum number of steps necessary is indicated over each reaction arrow.

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(•••) Synthesize the following molecules beginning with only organic molecules containing three carbons or fewer.

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(•••) Beginning with the molecules on the left, provide a synthesis of the molecule on the right. The ideal number of steps is indicated over the reaction arrow, although there may be alternate routes worth considering.

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Using the given starting material, any necessary inorganic reagents, and any carbon-containing compounds with no more than two carbons, indicate how the following syntheses could be carried out:

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Show how you would synthesize the following compounds.

As starting materials, you may use any alcohols containing

four or fewer carbon atoms, cyclohexanol, and any necessary

solvents and inorganic reagents.

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Show how you would synthesize the following compound.

As starting materials, you may use any alcohols containing five

or fewer carbon atoms and any necessary solvents

and inorganic reagents.

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a. Propose a mechanism for the following reaction.

2(CH3)2C=CH-CH3 + cat. H+--> 2,3,4,4-tetramethylhex-2-ene

b.Show the first three steps (as far as the tetramer) in the BF3 - catalyzed polymerization of propylene to form polypropylene.

Develop syntheses for the following compounds,

using acetylene and compounds con-taining no more than

four carbon atoms as your organic starting materials.

(a) 3-methylnon-4-yn-3-ol

(“3-ol” means there is an OH group on C3.)

Develop syntheses for the following compounds,

using acetylene and compounds con-taining no more than

four carbon atoms as your organic starting materials.

(b) cis-1-ethyl-2-methylcyclopropane

Show how you would synthesize each compound, starting with alkenes or cycloalkenes that contain no more than six carbon atoms. You may use any additional reagents you need.

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Propose mechanisms to explain the opposite regiochemistry observed in the following two reactions.

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Show how you would accomplish the following synthetic conversions.

c. 2−methylcyclohexanol → 1−bromo−1−methylcyclohexane

Work backward to show how the cyclopropane would be synthesized from the chloroalkane shown.

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For each of the following target molecules, design a multistep synthesis to show how it can be prepared from the given starting material:

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Identify A–E.

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Using cyclooctyne as your starting material,

show how you would synthesize the following compounds.

(Once you have shown how to synthesize a compound,

you may use it as the starting material in

any later parts of this problem.)

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Using cyclohexanone as the starting material, describe how each of the following compounds can be synthesized:

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Give the structures of the intermediates represented by letters in this synthesis.

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(•••) Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.

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Starting from bromobenzene and any other reagents and solvents you need, show how you would synthesize the following compounds. Any of these products may be used as starting materials in subsequent parts of this problem.

(d) 3-phenylprop-2-en-1-ol

Show how you would use Grignard syntheses to prepare the following alcohol from the indicated starting material and any other necessary reagents.

(e) benzyl alcohol (Ph-CH2 -OH) from bromobenzene (Ph¬Br)

Using cyclohexanone as the starting material, describe how each of the following compounds can be synthesized:

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How could the following compounds be prepared, using cyclohexene as a starting material?

a. <IMAGE>

Using the given starting material, any necessary inorganic reagents and catalysts, and any carbon-containing compounds with no more than three carbons,

indicate how each of the following compounds can be prepared:

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b. Which of the reactions cannot be used for the synthesis of isobutyl alcohol?

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For each synthesis, start with bromocyclohexane and predict the products. Assume that an excess of each reactant is added so that all possible reactions that can happen will happen.

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