Depending on the reaction conditions, two different imines

Give the IUPAC name and (if possible) a common name for each compound. \(\mathrm{CH}_{3}\) \(\mathrm{OH}\) \(\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{C}-\mathrm{CH}_{2} \mathrm{CH}_{3}\) \(\mathrm{CH}_{3}-\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CHO}\) \(\mathrm{OCH}_{3}\) Equation transcription: Text transcription: {CH}_{3} {OH} {CH}-{CH}_{2}-{C}-{CH}{2}{CH}{3} {CH}{3}-{CH}-{CH}{2}-{CHO} {OCH}{3}

Why were no products from McLafferty rearrangement observed in the spectrum of butan-2-one (Figure 18-3)?

Use equations to show the fragmentation leading to each numbered peak in the mass spectrum of octan-2-one.

Oxidation of cholesterol converts the alcohol to a ketone. Under acidic or basic oxidation conditions, the C = C double bond migrates to the more stable, conjugated position. Before IR and NMR spectroscopy, chemists watched the UV spectrum of the reaction mixture to follow the oxidation. Describe how the UV spectrum of the conjugated product, cholest-4-en- 3-one, differs from that of cholesterol. \(\mathrm{CH}_{3}\) \(H_{3} C\) \(\text { HO }\) Equation transcription: Text transcription: {CH}{3} H{3} C { HO }

NMR spectra for two compounds are given here, together with the molecular formulas. Each compound is a ketone or an aldehyde. In each case, show what characteristics of the spectrum imply the presence of a ketone or an aldehyde, and propose a structure for the compound.

(A true story.) The chemistry department custodian was cleaning the organic lab when an unmarked bottle fell off a shelf and smashed on the floor, leaving a puddle of volatile liquid. The custodian began to wipe up the puddle, but he was overcome with burning in his eyes and a feeling of having an electric drill thrust up his nose. He left the room and called the fire department, who used breathing equipment to go in and clean up the chemical. Three students were asked to identify the chemical quickly so the custodian could be treated and the chemical could be handled properly. The students took IR and NMR spectra, which follow. The UV spectrum showed \(\lambda_{\max }\) at 220 nm \((\epsilon=16,000)\). The mass spectrometer was down, so no molecular weight was available. Determine the structure of this nasty compound, and show how your structure fits the spectra. Equation transcription: Text transcription: lambda{max } (epsilon=16,000)

Show how you would synthesize each compound from starting materials containing no more than six carbon atoms. \(C H_{2} C H_{3}\) \(\mathrm{CH}_{2}-\mathrm{C}-\mathrm{CH}_{3}\) Equation transcription: Text transcription: C H_{2} C H_{3} {CH}{2}-{C}-{CH}{3}

Show how you would accomplish the following synthetic conversions by adding an organolithium reagent to an acid.

Predict the products of the following reactions. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C}=\mathrm{N}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{MgBr}\) then \(\mathrm{H}_{3} \mathrm{O}^{+}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C}=\mathrm{N}+\mathrm{DIBAL}-\mathrm{H}\), then \(\mathrm{H}_{3} \mathrm{O}^{+}\) (c) benzyl bromide + sodium cyanide (d) product of (c) + cyclopentylmagnesium bromide, then acidic hydrolysis (e) product of (c) + DIBAL-H, then hydrolysis Equation transcription: Text transcription: {CH}{3}{CH}{2}{CH}{2}{CH}{2}{C}={N}+{CH}{3}{CH}{2}{CH}{2}{MgBr} {CH}_{3} {CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2}{C}={N}+{DIBAL}-{H}

Show how the following transformations may be accomplished in good yield. You may use any additional reagents that are needed. (a) bromobenzene propiophenone (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CN}\) heptan-3-one (c) benzoic acid phenyl cyclopentyl ketone (d) 1-bromohept-2-ene oct-3-enal Equation transcription: Text transcription: {CH}{3}{CH}{2}{CN}

Predict the products of the following reactions:

Sodium triacetoxyborohydride, \(\mathrm{NaBH}(\mathrm{OAC})_{3}\), is a mild reducing agent that reduces aldehydes much more quickly than ketones. It can be used to reduce aldehydes in the presence of ketones, such as in the following reaction: \(\mathrm{CH}_{3}-\mathrm{C}-\mathrm{CH}_{2}-\mathrm{C}-\mathrm{H}\) \(\frac{\mathrm{NaBH}(O A C)_{3}}{\mathrm{CH}_{3} \mathrm{COOH}}\) \(C H_{3}-C-C H_{2}-C H_{2}\) (a) Draw a complete Lewis structure for sodium triacetoxyborohydride. (b) Propose a mechanism for the reduction of an aldehyde by sodium triacetoxyborohydride. Equation transcription: Text transcription: {NaBH}({OAC}){3} {CH}{3}-{C}-{CH}{2}-{C}-{H} frac{{NaBH}(O A C){3}}{{CH}{3} {COOH}} C H{3}-C-C H{2}-C H{2}

Show how you would accomplish the following synthetic conversions. You may use any additional reagents and solvents you need. \(P h-C H O \rightarrow P h-C-P h\) \(P h-C-P h \rightarrow P h_{3} C-O H\) \(P h-C-P h \rightarrow P h-C H-P h\) \(\text { PhCHO } \rightarrow \text { PhCHC }=\mathrm{CCH}_{2} \mathrm{CH}_{3}\) Equation transcription: Text transcription: P h-C H O rightarrow P h-C-P h P h-C-P h rightarrow P h{3} C-O H P h-C-P h rightarrow P h-C H-P h { PhCHO } rightarrow { PhCHC }={CCH}{2}{CH}{3}

Problem 13P Trimethylphosphine is a stronger nucleophile than triphenylphosphine, but it is rarely used to make ylides. Why is trimethylphosphine unsuitable for making most phosphorus ylides?

Problem 14P Like other strong nucleophiles, triphenylphosphine attacks and opens epoxides. The initial product (a betaine) quickly cyclizes to an oxaphosphetane that collapses to an alkene and triphenylphosphine oxide. (a) Show each step in the reaction of trans-2,3-epoxybutane with triphenylphosphine to give but-2-ene. What is the stereochemistry of the double bond in the product? (b) Show how this sequence might be used to convert cis-cyclooctene to trans-cyclooctene.

(a) Outline the syntheses indicated in Solved Problem 18-2, beginning with aldehydes and alkyl halides. (b) Both of these syntheses of 1-phenylbuta-1,3-diene form the central double bond. Show how you would synthesize this target molecule by forming the terminal double bond.

Show how Wittig reactions might be used to synthesize the following compounds. In each case, start with an alkyl halide and a ketone or an aldehyde. \(P h-C H=C\left(C H_{3}\right)_{2}\) \(P h-C\left(C H_{3}\right)=C H_{2}\) \(P h-C H=C H-C H=C H-P h\) \(\mathrm{CH}_{3}\) Equation transcription: Text transcription: P h-C H=C(C H{3}){2} P h-C(C H{3})=C H{2} P h-C H=C H-C H=C H-P h {CH}{3}

Problem 17P Propose mechanisms for (a) The acid-catalyzed hydration of chloral to form chloral hydrate. (b) The base-catalyzed hydration of acetone to form acetone hydrate.

Rank the following compounds in order of increasing amount of hydrate present at equilibrium. \(\mathrm{CHO}\) \(B r\) Equation transcription: Text transcription: {CHO} B r

Propose a mechanism for each cyanohydrin synthesis just shown.

Show how you would accomplish the following syntheses. (a) acetophenone acetophenone cyanohydrin (b) cyclopentanecarbaldehyde 2-cyclopentyl-2-hydroxyacetic acid (c) hexan-1-ol 2-hydroxyheptanoic acid

Problem 21P Propose mechanisms for the three imine-forming reactions just shown.

Depending on the reaction conditions, two different imines of formula \(C_{8} H_{9} N\) might be formed by the reaction of benzaldehyde with methylamine. Explain, and give the structures of the two imines. Equation transcription: Text transcription: C{8} H{9} N

Give the structures of the carbonyl compound and the amine used to form the following imines. \(\mathrm{CH}_{3}\) \(N=C H C H_{3}\) Equation transcription: Text transcription: {CH}{3} N=C H C H{3}

Problem 24P Propose a mechanism for the hydrolysis of benzaldehyde methyl imine just shown.

Problem 25P 2,4-Dinitrophenylhydrazine is frequently used for making derivatives of ketones and aldehydes because the products (2,4-dinitrophenylhydrazones, called 2,4-DNP derivatives) are even more likely than the phenylhydrazones to be solids with sharp melting points. Propose a mechanism for the reaction of acetone with 2,4-dinitrophenylhydrazine in a mildly acidic solution.

Predict the products of the following reactions. \(\mathrm{HONH}_{2}\) \(H_{2} N N H_{2}\) \(P h-C-P h+P h N H N H_{2}\) \(P h C H=C H C H O+H_{2} N C N H N H_{2}\) Equation transcription: Text transcription: {HONH}{2} H{2} N N H{2} P h-C-P h+P h N H N H_{2} P h C H=C H C H O+H{2} N C N H N H{2}

Show what amines and carbonyl compounds combine to give the following derivatives. \(P h-C H=N-N H-C-N H_{2}\) \(\text { NHPh }\) \(O_{2} N\) \(\mathrm{NO}_{2}\) \(\mathrm{CH}_{3}\) Equation transcription: Text transcription: P h-C H=N-N H-C-N H{2} { NHPh } O{2} N {NO}{2} {CH}{3}

Problem 28P Propose a mechanism for the acid-catalyzed reaction of benzaldehyde with methanol to give benzaldehyde dimethyl acetal.

Problem 29P Propose a mechanism for the acid-catalyzed hydrolysis of cyclohexanone dimethyl acetal.

Show what alcohols and carbonyl compounds give the following derivatives. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}\) \(\mathrm{OCH}_{2} \mathrm{CH}_{3}\) \(\mathrm{CH}_{3}\) Equation transcription: Text transcription: {CH}{3}{CH}{2}{O} {OCH}{2}{CH}{3} {CH}{3}

Problem 31P In the mechanism for acetal hydrolysis shown, the ring oxygen atom was protonated first, the ring was cleaved, and then the methoxy group was lost. The mechanism could also be written to show the methoxy oxygen protonating and cleaving first, followed by ring cleavage. Draw this alternative mechanism.

(a) Propose a mechanism for the acid-catalyzed reaction of cyclohexanone with ethylene glycol to give cyclohexanone ethylene acetal. (b) Propose a mechanism for the acid-catalyzed hydrolysis of cyclohexanone ethylene acetal. (c) Compare the mechanisms you drew in parts (a) and (b). How similar are these mechanisms, comparing them in reverse order? (d) Propose a mechanism for the acid-catalyzed hydrolysis of the acetal given in Problem 18-30(f). \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}\) \(\mathrm{OCH}_{2} \mathrm{CH}_{3}\) \(C H_{3}\) Equation transcription: Text transcription: {CH}{3}{CH}{2}{O} {OCH}{2}{CH}{3} C H{3}

Show how you would accomplish the following syntheses. You may use whatever additional reagents you need. \(\mathrm{CH}_{2} \mathrm{OH}\) \(\mathrm{CH}_{2} \mathrm{Br}\) \(\mathrm{CH}_{3}\) \(C H_{2}-C-P h\) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CCH}_{3} \rightarrow \mathrm{HC}=\mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{CCH}_{3}\) Equation transcription: Text transcription: {CH}{2}{OH} {CH}{2}{Br} {CH}{3} C H{2}-C-P h {BrCH}{2} {CH}{2}{CCH}{3} rightarrow{HC}={CCH}{2}{CH}{2}{CCH}{3}

Predict the major products of the following reactions. \(A g_{2} O) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} / \mathrm{H}_{2} \mathrm{SO}_{4}\) \(A g\left(N H_{3}\right)_{2}-O H\) \(\mathrm{KMnO}_{4}\) Equation transcription: Text transcription: A g{2} O {K}{2}{Cr}{2}{O}{7} /{H}{2}{SO}{4} A g(N H{3}){2}-O H {KMnO}{4}

Problem 35P Propose a mechanism for both parts of the Wolff–Kishner reduction of cyclohexanone: the formation of the hydrazone, then the base-catalyzed reduction with evolution of nitrogen gas.

Predict the major products of the following reactions: \(\frac{Z n(H g)}{H C I, H_{2} O}\) \(\frac{H_{2} N N H_{2}}{K O H, h e a t}\) \(\frac{N_{2} H_{4}}{K O H, \text { heat }}\) \(\frac{\mathrm{Zn}(\mathrm{Hg})}{\mathrm{HCl}, \mathrm{H}_{2} \mathrm{O}}\) Equation transcription: Text transcription: frac{Z n(H g)}{H C I, H{2} O} frac{H{2} N N H{2}}{K O H, h e a t} frac{N{2} H{4}}{K O H,{ heat }} frac{{Zn}({Hg})}{{HCl},{H}{2}{O}}

Name the following ketones and aldehydes. When possible, give both a common name and an IUPAC name. 1. \(\mathrm{CH}_{3} \mathrm{CO}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{3}\) 2. \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{2} \mathrm{CO}\left(\mathrm{CH}_{2}\right)_{2} \mathrm{CH}_{3}\) 3. \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{5} \mathrm{CHO}\) 4. \(\text { PhCOPh }\) 5. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}\) 6. \(\mathrm{CH}_{3} \mathrm{COCH}_{3}\) 7. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHBrCH}_{2} \mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CHO}\) 8. \(\P h-C H=C H-C H O) 9. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}-\mathrm{CHO}\) Equation transcription: Text transcription: {CH}{3}{CO}({CH}{2}){4}{CH}{3} {CH}{3}({CH}{2}){2}{CO}({CH}{2}){2}{CH}{3} {CH}_{3}({CH}{2}){5}{CHO} { PhCOPh } {CH}{3}{CH}{2}{CH}{2}{CHO} {CH}{3}{COCH}_{3} {CH}{3}{CH}{2}{CHBrCH}{2}{CH}({CH}{3}){CHO} P h-C H=C H-C H O {CH}{3}{CH}={CH}-{CH}={CH}-{CHO}

Problem 37SP Draw structures of the following derivatives. (a) the 2,4-dinitrophenylhydrazone of benzaldehyde (b) the semicarbazone of cyclobutanone (c) cyclopropanone oxime (d) the ethylene acetal of hexan-3-one (e) acetaldehyde dimethyl acetal (f) the methyl hemiacetal of formaldehyde (g) the (E) isomer of the ethyl imine of propiophenone (h) the hemiacetal form of 5-hydroxypentanal

Predict the major products of the following reactions.

Problem 40SP Rank the following carbonyl compounds in order of increasing equilibrium constant for hydration: CH3COCH2Cl ClCH2CHO CH2O CH3COCH3 CH3CHO

Acetals can serve as protecting groups for 1,2-diols, as well as for aldehydes and ketones. When the acetal is formed from acetone plus the diol, the acetal is called an acetonide. Show the acetonides formed from these diols with acetone under acid catalysis. \(O H\) \(\text { ?? }\) Equation transcription: Text transcription: O H { ?? }

Problem 42SP Sketch the expected proton NMR spectrum of 3,3-dimethylbutanal.

The proton NMR spectrum of a compound of formula \(C_{10} H_{12} O\) follows. This compound reacts with an acidic solution of 2,4-dinitrophenylhydrazine to give a crystalline derivative, but it gives a negative Tollens test. Propose a structure for this compound and give peak assignments to account for the signals in the spectrum. Equation transcription: Text transcription: C{10} H{12} O

Problem 43SP A compound of formula C6H10O2shows only two absorptions in the proton NMR: a singlet at 2.67 ppm and a singlet at 2.15 ppm. These absorptions have areas in the ratio 2:3. The IR spectrum shows a strong absorption at 1708 cm-1 .Propose a structure for this compound.

Problem 45SP The following compounds undergo McLafferty rearrangement in the mass spectrometer. Predict the masses of the resulting charged fragments. (a) pentanal (b) 3-methylhexan-2-one (c) 4-methylhexan-2-one

An unknown compound gives a molecular ion of ????/???? 70 in the mass spectrum. It reacts with semicarbazide hydrochloride to give a crystalline derivative, but it gives a negative Tollens test. The NMR and IR spectra follow. Propose a structure for this compound, and give peak assignments to account for the absorptions in the spectra. Explain why the signal at \(1790 \mathrm{~cm}^{-1}\) in the IR spectrum appears at an unusual frequency. Equation transcription: Text transcription: 1790{~cm}^{-1}

Show how you would accomplish the following synthetic conversions efficiently and in good yield. You may use any necessary additional reagents and solvents. \(\mathrm{OCH}_{3}\) \(\mathrm{CH}_{2} \mathrm{Br}\) \(\mathrm{COOH}\) \(\mathrm{CH}_{2} \mathrm{OH}) \(\mathrm{CH}_{3}\) \(\mathrm{CHO}\) Equation transcription: Text transcription: {OCH}{3} {CH}{2}{Br} {COOH} {CH}{2}{OH} {CH}{3} {CHO}

The following road-map problem centers on the structure and properties of A, a key intermediate in these reactions. Give structures for compounds A through J.

For each compound, 1. Name the functional group. 2. Show what compound(s) result from complete hydrolysis. \(\mathrm{CH}_{3} \mathrm{O}\) \(\mathrm{OCH}_{3}\) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2}-\mathrm{C}-\mathrm{CH}_{3}\) \(\mathrm{OCH}_{2} \mathrm{CH}_{3}\) \(\mathrm{NNH}_{2}\) Equation transcription: Text transcription: {CH}{3}{O} {OCH}{3} {CH}{3}{CH}{2}{CH}{2}-{C}-{CH}{3} {OCH}{2}{CH}{3} {NNH}{2}

Propose mechanisms for the following reactions.

Show how you would accomplish the following syntheses efficiently and in good yield. You may use any necessary reagents. \(\mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{COOH}\) \(\text { CHPh }\) \(\mathrm{CH}_{2} \mathrm{OH}\) \(\mathrm{CHCH}_{2} \mathrm{CH}_{3}\) Equation transcription: Text transcription: {CH}{3}{CH}({OH}){COOH} { CHPh } {CH}_{2}{OH} {CHCH}{2}{CH}{3}

Show how you would synthesize the following derivatives from appropriate carbonyl compounds. \(N-O H\) \(\mathrm{CH}_{3} \mathrm{O}\) \(\mathrm{OCH}_{3}\) Equation transcription: Text transcription: N-O H {CH}{3}{O} {OCH}{3}

Predict the products formed when cyclohexanone reacts with the following reagents. \(\mathrm{CH}_{3} \mathrm{NH}_{2}, \mathrm{H}^{+}\) \(\mathrm{CH}_{3} \mathrm{OH}, \mathrm{H}^{+}\) \(\mathrm{H}_{3} \mathrm{O}^{+}\) \(P h_{3} P=C H_{2}\) Equation transcription: Text transcription: {CH}{3}{NH}{2},{H}^{+} {CH}{3}{OH},{H}^{+} {H}{3}{O}^{+} P h{3} P=C H{2}

Problem 55SP Show how you would synthesize octan-2-one from each compound. You may use any necessary reagents. (a) heptanal (b) oct-1-yne (c) 2,3-dimethylnon-2-ene (d) octan-2-ol (e) heptanoic acid (f) CH3(CH2)5CN

Problem 54SP Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents. (a) PhMgBr, then H3O+ (b) Tollens reagent (c) semicarbazide and weak acid (d) excess ethanol and acid (e) propane-1,3-diol, H+ (f) zinc amalgam and dilute hydrochloric acid

Problem 56SP Show how you would synthesize octanal from each compound. You may use any necessary reagents. (a) octan-1-ol (b) non-1-ene (c) oct-1-yne (d) 1-bromoheptane (e) 1-bromohexane (f) octanoic acid (g) ethyl octanoate

Both \(\mathrm{NaBH}_{4}\) and \(\mathrm{NaBD}_{4}\) are commercially available, and \(D_{2} O\) is common and inexpensive. Show how you would synthesize the following labeled compounds, starting with butan-2-one. Equation transcription: Text transcription: {NaBH}{4} {NaBD}{4} D{2} O

Problem 58SP When LiAIH4 reduces 3-methylcyclopentanone, the product mixture contains 60% cis-3-methylcyclopentanol and 40% trans-3-methylcyclopentanol. Use your models and make three-dimensional drawings to explain this preference for the cis isomer.

The Wittig reaction is useful for placing double bonds in less stable positions. For example, the following transformation is easily accomplished using a Wittig reaction. \(\mathrm{CH}_{2}\) (a) Show how you would use a Wittig reaction to do this. (b) Show how you might do this without using a Wittig reaction, and explain why the Wittig reaction is a much better synthesis. Equation transcription: Text transcription: {CH}{2}

Show how you would accomplish the following syntheses. (a) benzene????-butylbenzene (b) benzonitrilepropiophenone (c) benzene????-methoxybenzaldehyde \(P h-\left(C H_{2}\right)_{4}-O H\) Equation transcription: Text transcription: P h-(C H{2}){4}-O H

There are three dioxane isomers: 1,2-dioxane, 1,3-dioxane, and 1,4-dioxane. One of these acts like an ether and is an excellent solvent for Grignard reactions. Another one is potentially explosive when heated. The third one quickly hydrolyzes in dilute acid. Show which isomer acts like a simple ether, and explain why one of them is potentially explosive. Propose a mechanism for the acid hydrolysis of the third isomer.

Problem 62SP Two structures for the sugar glucose are shown on page 858. Interconversion of the open-chain and cyclic hemiacetal forms is catalyzed by either acid or base. (a) Propose a mechanism for the cyclization, assuming a trace of acid is present. (b) The cyclic hemiacetal is more stable than the open-chain form, so very little of the open-chain form is present at equilibrium. Will an aqueous solution of glucose reduce Tollens reagent and give a positive Tollens test? Explain.

Two structures of the sugar fructose are shown next. The cyclic structure predominates in aqueous solution. (a) Number the carbon atoms in the cyclic structure. What is the functional group at C2 in the cyclic form? (b) Propose a mechanism for the cyclization, assuming a trace of acid is present.

Problem 64SP Hydration of alkynes (via oxymercuration) gives good yields of single compounds only with symmetrical or terminal alkynes. Show what the products would be from hydration of each compound. (a) hex-3-yne (b) hex-2-yne (c) hex-1-yne (d) cyclodecyne (e) 3-methylcyclodecyne

Which of the following compounds would give a positive Tollens test? (Remember that the Tollens test involves mild basic aqueous conditions.) 1. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COCH}_{3}\) 2. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}\) 3. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}=\mathrm{CHOH}\) 4. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{OH}) \mathrm{OCH}_{3}\) 5. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{OCH}_{3}\right)_{2}\) Equation transcription: Text transcription: {CH}{3}{CH}{2}{CH}{2}{COCH}_{3} {CH}{3}{CH}{2}{CH}{2}{CH}{2} {CHO} {CH}{3}{CH}={CHCH}={CHOH} {CH}{3}{CH}{2}{CH}{2}{CH}{2}{CH}({OH}){OCH}{3} {CH}{3}{CH}{2}{CH}{2}{CH}{2}{CH}({OCH}{3}){2}

Solving the following road-map problem depends on determining the structure of A, the key intermediate. Give structures for compounds A through K.

(a) Simple aminoacetals hydrolyze quickly and easily in dilute acid. Propose a mechanism for hydrolysis of the following aminoacetal: \(\mathrm{N}\left(\mathrm{CH}_{3}\right)_{2}\) \(\mathrm{H}_{3} \mathrm{O}^{+}\) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}_{2}\) (b) The nucleosides that make up DNA have heterocyclic rings linked to deoxyribose by an aminoacetal functional group. Point out the aminoacetal linkages in deoxycytidine and deoxyadenosine. \(N H_{2}\) \(\mathrm{HOH}_{2} \mathrm{C}\) (c) The stability of our genetic code depends on the stability of DNA. We are fortunate that the aminoacetal linkages of DNA are not easily cleaved. Show why your mechanism for part (a) does not work so well with deoxycytidine and deoxyadenosine. Equation transcription: Text transcription: {N}({CH}{3}){2} {H}{3}{O}^{+} ({CH}{3}){2}{NH}{2} N H{2} {HOH}{2}{C}

The mass spectrum of unknown compound A shows a molecular ion at ????/???? 116 and prominent peaks at ????/???? 87 and ????/???? 101. Its UV spectrum shows no maximum above 200 nm. The IR and NMR spectra of A follow. When A is washed with dilute aqueous acid, extracted into dichloromethane, and the solvent evaporated, it gives a product B. B shows a strong carbonyl signal at \(1715 \mathrm{~cm}^{-1}\) in the IR spectrum and a weak maximum at \(274 \mathrm{~mm}(\mathrm{E}=16)\) in the UV spectrum. The mass spectrum of B shows a molecular ion of ????/???? 72. Determine the structures of A and B, and show the fragmentation to account for the peaks at ????/???? 87 and 101. Equation transcription: Text transcription: 1715{~cm}^{-1} 274{~mm}({E}=16)

The UV spectrum of an unknown compound shows values of \(\lambda_{\max }\) at \(225 \mathrm{~nm}(\epsilon=10,000)\) and at \(318 n m(\epsilon=40)\). The mass spectrum shows a molecular ion at ????/???? 96 and a prominent base peak at ????/???? 68. The IR and NMR spectra follow. Propose a structure, and show how your structure corresponds to the observed absorptions. Propose a favorable fragmentation to account for the MS base peak at ????/???? 68 (loss of \(C_{2} H_{4}\)). Equation transcription: Text transcription: lambda{max } 225{~nm}(epsilon=10,000) 318 n m(epsilon=40) C{2} H{4}