Aldehydes and Ketones: Nucleophilic Addition Reactions

How would you synthesize the following compounds from cyclohexanone?

1. 1-Methylcyclohexene
2. 2-Phenylcyclohexanone
3. cis-1,2-Cyclohexanediol
4. 1-Cyclohexylcyclohexanol

At what position would you expect to observe IR absorptions for the following molecules?

a. 

b.

c. 

d.

Acid-catalyzed dehydration of 3-hydroxy-3-phenylcyclohexanone leads to an unsaturated ketone. What possible structures are there for the product? At what position in the IR spectrum would you expect each to absorb? If the actual product has an absorption at $\mathbf{1670}{\mathbf{cm}}^{-1}$, what is its structure?

Choose the structure that best fits the IR spectrum shown.

Propose structures for molecules that meet the following descriptions.

Assume that the kinds of carbons (1°, 2°, 3°, or 4°) have been assigned

by DEPT–NMR.

(a)${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{12}}\mathbf{O}$; IR: 1715${\mathrm{cm}}^{-1}$; ¹³C NMR: 8.0$\mathbf{\delta }$ (1°), 18.5$\mathbf{\delta }$ (1°), 33.5$\mathbf{\delta }$(2°),

40.6$\mathbf{\delta }$ (3°), 214.0 $\mathbf{\delta }$(4°)

(b)${\mathbf{C}}_{\mathbf{5}}{\mathbf{H}}_{\mathbf{10}}\mathbf{O}$; IR: 1730${\mathrm{cm}}^{-1}$; ¹³C NMR: 22.6 $\mathbf{\delta }$(1°), 23.6$\mathbf{\delta }$ (3°), 52.8$\mathbf{\delta }$ (2°),

202.4 (3°)

(c)${\mathbf{C}}_6{\mathbf{H}}_8\mathbf{O}$; IR: 1680${\mathrm{cm}}^{-1}$; ¹³C NMR: 22.9$\mathbf{\delta }$(2°), 25.8$\mathbf{\delta }$ (2°), 38.2$\mathbf{\delta }$ (2°),

129.8 d (3°), 150.6 $\mathbf{\delta }$(3°), 198.7$\mathbf{\delta }$ (4°)

Compound A, ${\mathbf{C}}_8{\mathbf{H}}_{10}{\mathbf{O}}_2$, has an intense IR absorption at 1750${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$ and gives the ¹³C NMR spectrum shown. Propose a structure for A.

Propose structures for ketones or aldehydes that have the following ¹H

NMR spectra:

(a) ${\mathbf{C}}_4{\mathbf{H}}_7\mathbf{ClO}$

      IR: 1715 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$

(b) ${\mathbf{C}}_7{\mathbf{H}}_{14}\mathbf{O}$

IR: 1710 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$

When 4-hydroxybutanal is treated with methanol in the presence of an acid catalyst, 2-methoxytetrahydrofuran is formed. Explain

The S_N2 reaction of (dibromomethyl)benzene, C₆H₅CHBr₂, with NaOH yields benzaldehyde rather than (dihydroxymethyl)benzene, C₆H₅CH(OH)₂. Explain.

Reaction of 2-butanone with HCN yields a chiral product. What stereochemistry does the product have? Is it optically active?

The amino acid methionine is biosynthesized by a multistep route that includes reaction of an imine of pyridoxal phosphate (PLP) to give an unsaturated imine, which then reacts with cysteine. What kinds of reactions are occurring in the two steps?

Each of the following reaction schemes contains one or more flaws.

What is wrong in each case? How would you correct each scheme?

(a)

(b)

(c)

6-Methyl-5-hepten-2-one is a constituent of lemongrass oil. How could you synthesize this substance from methyl 4-oxopentanoate?

Methyl 4-oxopentanoate

Tamoxifen is a drug used in the treatment of breast cancer. How would you prepare tamoxifen from benzene, the following ketone, and any other reagents needed?

Compound A, M⁺ = 86, shows an IR absorption at 1730 cm^-and a very simple ¹HNMR spectrum with peaks at 9.7 $\delta$(1 H, singlet) and 1.2 $\delta$(9 H, singlet). Propose a structure for A.

Compound B is isomeric with A (Problem 19-79) and shows an IR peak at 1715 cm^-1. The ¹HNMR spectrum of B has peaks at 2.4 $\delta$ (1 H, septet, J = 7 Hz), 2.1 $\delta$ (3 H, singlet), and 1.2 $\delta$ (6 H, doublet, J =7 Hz). What is

the structure of B?

The ¹HNMR  spectrum shown is that of a compound with the formula C₉H₁₀O. How many double bonds and/or rings does this compound contain? If the unknown compound has an IR absorption at 1690 cm^-1. , what is a likely structure? 

The ¹HNMR   spectrum shown is that of a compound isomeric with the one in Problem 19-81. This isomer has an IR absorption at 1730 cm^-1. Propose a structure.

[Note: Aldehyde protons (CHO) often show low coupling constants to adjacent hydrogens, so the splitting of aldehyde signals is not always apparent.]

Propose structures for ketones or aldehydes that have the following ¹H NMR   spectra: 

(a) C₉H₁₀O₂  

      IR: 1695 cm^-1

(b) C₄H₆O 

     IR: 1690 cm^-1

Propose structures for ketones or aldehydes that have the following ${}^{\mathbf{1}}\mathbf{H}$ NMR spectra:

 (a)C₁₀H₁₂O 

$\mathit{I}\mathit{R}\mathbf{:}\mathbf{ }\mathbf{1710}\mathbf{ }\mathit{c}{\mathit{m}}^{\mathbf{-}\mathbf{1}}$

(b) ${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{12}}{\mathbf{O}}_{\mathbf{3}}$

$\mathbf{IR}\mathbf{:}\mathbf{ }\mathbf{1715}\mathbf{ }{\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$

Propose structures for ketones or aldehydes that have the following \(^1H\;NMR\)  spectra: 

(a) \({C_{10}}{H_{12}}O\)  

      IR: 1710 \(c{m^{ - 1}}\)

(b) \({C_6}{H_{12}}{O_3}\) 

     IR: 1715 \(c{m^{ - 1}}\)

When glucose (Problem 19-52) is treated with NaBH₄ , reaction occurs to yield sorbitol, a polyalcohol commonly used as a food additive. Show how this reduction occurs.

When glucose (Problem 19-52) is treated with \(NaB{H_4}\), reaction occurs to yield sorbitol, a polyalcohol commonly used as a food additive. Show how this reduction occurs.

The proton and carbon NMR spectra for each of three isomeric ketones with the formula C₇H₁₄O are shown below. Assign a structure to each pair of spectra.

The proton NMR spectrum for a compound with formula C₁₀H₁₂O₂ is shown below. The infrared spectrum has a strong band at . The broadband-decoupled ¹³C NMR spectral results are tabulated along with the DEPT-135 and DEPT-90 information. Draw the structure of this compound.

The proton NMR spectrum for a compound with formula  is shown below. The infrared spectrum has a strong band at . The broadband-decoupled  NMR spectral results are tabulated along with the DEPT-135 and DEPT-90 information. Draw the structure of this compound.