Oxidation and Reduction

Question: Identify the starting material in each reaction.

a.

b.

Question: Draw the products formed when each naturally occurring compound is treated with ${\mathit{O}}_{\mathbf{3}}$ followed by Zn,${\mathit{H}}_{\mathbf{2}}\mathit{O}$.

Question: Identify compounds A, B, and C.

a. Compound A has molecular formula ${\mathit{C}}_{\mathbf{8}}{\mathit{H}}_{\mathbf{12}}$  and reacts with two equivalents of ${\mathit{H}}_{\mathbf{2}}$. A gives $\mathit{H}\mathit{C}\mathit{O}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{H}\mathit{O}$ as the only product of oxidative cleavage with ${\mathit{O}}_{\mathbf{3}}$ followed by $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{S}\mathit{C}{\mathit{H}}_{\mathbf{3}}$.

b. Compound B has molecular formula ${\mathit{C}}_{\mathbf{6}}{\mathit{H}}_{\mathbf{10}}$ and gives ${\left(C{H}_3\right)}_{\mathbf{2}}\mathit{C}\mathit{H}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}{\mathit{H}}_{\mathbf{3}}$  when treated with excess ${\mathit{H}}_{\mathbf{2}}$  in the presence of Pd. B reacts with $\mathit{N}\mathit{a}\mathit{N}{\mathit{H}}_{\mathbf{2}}$ and $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{I}$ to form compound C (molecular formula  ${\mathit{C}}_{\mathbf{7}}{\mathit{H}}_{\mathbf{12}}$).

Question: Oximene and myrcene, two hydrocarbons isolated from alfalfa that have the molecular formula ${\mathit{C}}_{\mathbf{10}}{\mathit{H}}_{\mathbf{16}}$ , both yield 2,6-dimethyloctane when treated with  ${\mathit{H}}_{\mathbf{2}}$ and a Pd catalyst. Ozonolysis of oximene forms ${\left(C{H}_3\right)}_{\mathbf{2}}\mathit{C}\mathbf{=}\mathit{O}$ , $\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathbf{=}\mathit{O}$ , $\mathit{C}{\mathit{H}}_{\mathbf{2}}{\left(CHO\right)}_{\mathbf{2}}$ and $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}\mathit{O}\mathit{C}\mathit{H}\mathit{O}$. Ozonolysis of myrcene yields ${\left(C{H}_3\right)}_{\mathbf{2}}\mathit{C}\mathit{O}$, $\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathbf{=}\mathit{O}$ (two equiv), and $\mathit{H}\mathit{C}\mathit{O}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{O}\mathit{C}\mathit{H}\mathit{O}$. Identify the structures of oximene and myrcene.

Question: An unknown compound A of molecular formula ${\mathit{C}}_{\mathbf{10}}{\mathit{H}}_{\mathbf{18}}\mathit{O}$  reacts with ${\mathit{H}}_{\mathbf{2}}\mathit{S}{\mathit{O}}_{\mathbf{4}}$  to form two compounds (B and C) of molecular formula ${\mathit{C}}_{\mathbf{10}}{\mathit{H}}_{\mathbf{16}}$ . B and C both react with ${\mathit{H}}_{\mathbf{2}}$  in the presence of Pd-C to form decalin. Ozonolysis of B forms D, and ozonolysis of C forms a diketone E of molecular formula ${\mathit{C}}_{\mathbf{10}}{\mathit{H}}_{\mathbf{16}}{\mathit{O}}_{\mathbf{2}}$. Identify the structures of compounds A, B, C and E.

Question: DHA is a fatty acid derived from fish oil and an abundant fatty acid in vertebrate brains. Hydrogenation of DHA forms docosanoic acid $\left[C{H}_3{\left(C{H}_2\right)}_{2}OC{O}_{2}H\right]$ and ozonolysis forms $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{H}\mathit{O}\mathbf{,}\mathbf{ }\mathit{C}{\mathit{H}}_{\mathbf{2}}{\left(CHO\right)}_{\mathbf{2}}$ (five equivalents), and $\mathit{H}\mathit{C}\mathit{O}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}{\mathit{O}}_{\mathbf{2}}\mathit{H}$. What is the structure of DHA if all double bonds have the Z configuration?

Question: One compound that contributes to the “seashore smell”at beaches in Hawai’s is dictyopterene D’ with excess ${\mathit{H}}_{\mathbf{2}}$ in the presence of a Pd catalyst forms butylcycloheptane. Ozonolysis with ${\mathit{O}}_{\mathbf{3}}$  followed by  ${\left(C{H}_3\right)}_{\mathbf{2}}\mathit{S}$  forms $\mathit{C}{\mathit{H}}_{\mathbf{2}}{\left(CHO\right)}_{\mathbf{2}}$ ,$\mathit{H}\mathit{C}\mathit{O}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{H}{\left(CHO\right)}_{\mathbf{2}}$ , and $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{H}\mathit{O}$. What are possible structures of dictyopterene D’?

Question: Draw the product of each asymmetric epoxidation reaction.

Question: Epoxidation of the following allylic alcohol using the Sharpess reagent (-)-DET gives two epoxy alcohols in a ratio of 87:13.

1. Assign structures to the major and minor product.
2. What is the enantiomeric excess in this reaction?

Question: What allylic alcohol and DET isomer are needed to make each chiral epoxide using a sharpless asymmetric epoxidation reaction?

Question: Identify A in the following reaction sequence and draw a mechanism for the conversion of A to B. B has been converted to (S,S)-reboxetine, an antidepressant marketed outside the United States.

Question: Devise a synthesis of muscalure, the sex pheromone of the common housefly, from acetylene and any other required reagents.

                                                  Muscalure

Question: It is sometimes necessary to isomerize a cis alkene to a trans alkene in a synthesis, a process that cannot be accomplished in a single step. Using the reactions that you have learned in Chapters 8–12, devise a stepwise method to convert cis-but-2-ene to trans-but-2-ene.

Question: Devise a synthesis of each compound from acetylene and any other required reagents.

Question: Devise a synthesis of compound A from the given starting materials. You may use any other inorganic reagents or organic alcohols. A was used to prepare aliskiren, a drug used to treat hypertension (see also Problem 5.7).

Question: Devise a synthesis of (E)-hex-2-ene from pent-1-ene and any needed organic compounds or inorganic reagents.

Question: Devise a synthesis of each compound from the indicated starting material, organic compounds containing one or two carbons, and any other required reagents.

Question:Devise a synthesis of 1-phenyl-5-methylhexane $\left[C_6{H}_5{\left(C{H}_2\right)}_{4}CH{\left(C{H}_3\right)}_2\right]$ from acetylene, alkylhalides, and any required inorganic reagents.

Question: Devise a synthesis of (3R,4S)-3,4-dichlorohexane from acetylene and any needed organic compounds or inorganic reagents.

Question: Devise a synthesis of each compound from $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{O}\mathit{H}$ as the only organic starting material; that is, every carbon in the product must come from a molecule of ethanol. You may use any other needed inorganic reagents.

Question: The Birch reduction is a dissolving metal reaction that converts substituted benzenes to cyclohexa-1,4-dienes using Li and liquid ammonia in the presence of an alcohol. Draw a stepwise mechanism for the following Birch reduction.

Question: Draw a stepwise mechanism for the following reaction.

Question: Dihydroxylation of an alkene can be carried out with ${\mathit{H}}_{\mathbf{2}}{\mathit{O}}_{\mathbf{2}}$  in $\mathit{H}\mathit{C}{\mathit{O}}_{\mathbf{2}}\mathit{H}$. In this reaction, transbut-2-ene affords (2R,3S)-butane-2,3-diol, whereas cis-but-2-ene affords a mixture of (2R,3R)-butane-2,3-diol and (2S,3S)-butane-2,3-diol. Does dihydroxylation by this method occur with syn or anti addition?

Question: Draw a stepwise mechanism for the following reaction.

Question: Sharpless epoxidation of allylic alcohol X forms compound Y. Treatment of Y with NaOH and ${\mathit{C}}_{\mathbf{6}}{\mathit{H}}_{\mathbf{5}}\mathit{S}\mathit{H}$  in an alcohol–water mixture forms Z. Identify the structure of Y and draw a mechanism for the conversion of Y to Z. Account for the stereochemistry of the stereogenic centers in Z. Z has been used as an intermediate in the synthesis of chiral carbohydrates.