Question 1

Complete the structure on the right by adding groups to the "dangling bonds" to give the product of the chair flip.

Accepted Answer

Upon a chair flip, the equatorial substituents flip to become axial substituents, and vice versa. There are two possible orientations you could have drawn.

Question 2

Alkaline potassium permanganate (an achiral reagent) adds two -OH groups to a double bond, as shown in the reaction.
  This reaction is known to be a syn-addition. This means that cis-2-pentene will give as product

Accepted Answer

A)  (2S,3S)-2,3-pentanediol. 
B)  the racemate of the compound in a. 
C)  (2R,3S)-2,3-pentanediol. 
D)  the racemate of the compound in c. 
E)  meso-2,3-pentanediol. 
A)  (2S,3S)-2,3-pentanediol. 
B)  the racemate of the compound in a. 
C)  (2R,3S)-2,3-pentanediol. 
D)  the racemate of the compound in c. 
E)  meso-2,3-pentanediol. D

Question 3

Olean is the sex attractant of the fruit fly. The female emits this compound to signal her readiness for mating. (This has been used to control fruit-fly populations in orchards.) (The numbers on the structure are for reference in the questions below.)
   a. Determine whether olean is chiral. Explain how you know. No credit is given without a credible explanation, which should include structures.
b. Does olean have any stereocenters?
If you determined that olean has stereocenters, how many does it have? If none, write NONE.
c. Does olean have any asymmetric carbons?
If you determined that olean has asymmetric carbons, how many does it have? If none, write NONE.

Accepted Answer

Olean is a spirocyclic compound where two rings share a carbon, but the carbon still has a tetrahedral configuration. The compound does not contain any asymmetric atoms, since none of the atoms are bonded to four different groups. It does have a stereocenter, carbon 6, since exchanging any of the two groups on carbon 6 will produce the opposite configuration. The chirality of Olean is a twist chirality, like the thread of a screw. You might find it easier to visualize the chirality of Olean by examining the planar molecule and its mirror image. We can view each end in a Newman projection, and you can see the alkyoxy groups turn to the right on one enantiomer and turns to the left on the other enantiomer.

Question 4

Limonene is a precursor to the biosynthesis of menthol-a component of peppermint oil. The structure of the levorotatory enantiomer of menthol is given.
  Which structure represents the dextrorotatory enantiomer of menthol?

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D

Question 5

An achiral alkene A with the molecular formula C8H16 reacts with B2H6, then H2O2/−OH, to give a single alcohol B, C8H18O, that can be resolved into enantiomers. When alkene A is subjected to Hg(OAc)2/H2O, then NaBH4, a single achiral alcohol C is obtained that has different properties from B but has the same formula. Reaction of A with O3, then H2O2/H2O, gives a ketone D (C7H14O) as one product. Catalytic hydrogenation of alkene A yields 3-ethyl-2-methylpentane. Deduce the structures of compounds A, B, C, and D, and be sure each structure is properly labeled.

Accepted Answer

Working backward from the catalytic hydr

Question 6

Which statement best describes the relationship of these two molecules?

Accepted Answer

A)  diastereomers that are meso compounds 
B)  diastereomers that are not meso compound 
C)  enantiomers that are meso compounds 
D)  enantiomers that are not meso compounds 
E)  identical molecules that are mesof. 
identical molecules that are not meso 
A)  diastereomers that are meso compounds 
B)  diastereomers that are not meso compound 
C)  enantiomers that are meso compounds 
D)  enantiomers that are not meso compounds 
E)  identical molecules that are mesof. 
identical molecules that are not meso

Question 7

Draw the two chair conformations of the hydrocarbon. Be sure you draw the correct enantiomer! Indicate the more stable of the two conformations.

Accepted Answer

The answer of Draw the two chair conformations of the...

Question 8

Examine the chair conformations A-F for the structure on the left.
   The two correct conformations of the hydrocarbon shown in the line and wedge form are compound ________________ and compound ________________. Of the two compounds you identified, compound ________________ is more stable.

Accepted Answer

The answer of Examine the chair conformations A-F for the...

Question 9

Draw the two chair conformations of the compound and circle the more stable conformation. Be sure to draw this compound and not its enantiomer.

Accepted Answer

The answer of Draw the two chair conformations of the...

Question 10

Which one of these molecules can readily undergo the chair-to-chair interconversion ("chair flip")?

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  compound Ef. 
compound F 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  compound Ef. 
compound F

Question 11

Draw the most stable chair conformation of each of the following alcohols.
 (a)

(b)

Accepted Answer

The answer of Draw the most stable chair conformation of...

Question 12

Complete the following reaction by giving the structure of the missing organic starting material.

Accepted Answer

The answer of Complete the following reaction by giving the...

Question 13

(a) Give the structures of all stereoisomers formed as products in the reaction. Draw only those isomers that are consistent with the known stereospecificity of the reaction! (D = deuterium = the isotope of hydrogen with atomic mass = 2.) (b) Are the stereoisomers you drew formed in the same or different amounts?

Accepted Answer

The reaction occurs as a syn-addition. T

Question 14

Complete the reaction by giving the structures of the missing organic products. (Ignore by-products.) (Note that D = deuterium, an isotope of hydrogen, that reacts like hydrogen.)

Accepted Answer

The answer of Complete the reaction by giving the structures...

Question 15

On the template, complete the other chair conformation of cis-1,3-dimethylcyclohexane and circle the more stable conformation.

Accepted Answer

The answer of On the template, complete the other chair...

Question 16

Fill in the chair template to show the ring flipped conformation of the structure on the left, numbering the carbons in the ring clockwise from the carbon labeled "1" (include hydrogens). Then circle the conformation that is the more stable.

Accepted Answer

In a chair flip, the axial sub

Question 17

The two conformations of the hydrocarbon given in planar form at the left are compound ________________ and compound ________________.
   The more stable conformation of these two is compound ________________.

Accepted Answer

The answer of The two conformations of the hydrocarbon given...

Question 18

For the structure:
   Fill in the bonds and group structures that show the positions of the three functional groups (two methyl groups and a tert-butyl group) using the templates for the chair and the 'flipped' chair conformations provided. You do not need to include hydrogens. Use the ring numbering as indicated.

Accepted Answer

The answer of For the structure:
   Fill in...

Question 19

Select the bridged bicyclic compound with the formula C8H12 that violates Bredt's rule.

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D

Question 20

Which one of these structures is a properly drawn chair conformation of trans-1,2-dimethylcyclohexane?

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  compound E 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  compound E

Exam 7: Cyclic Compounds and Reaction Stereochemistry

Complete the structure on the right by adding groups to the "dangling bonds" to give the product of the chair flip.

Alkaline potassium permanganate (an achiral reagent) adds two -OH groups to a double bond, as shown in the reaction. This reaction is known to be a syn-addition. This means that cis-2-pentene will give as product

Limonene is a precursor to the biosynthesis of menthol-a component of peppermint oil. The structure of the levorotatory enantiomer of menthol is given. Which structure represents the dextrorotatory enantiomer of menthol?

Which statement best describes the relationship of these two molecules?

Draw the two chair conformations of the hydrocarbon. Be sure you draw the correct enantiomer! Indicate the more stable of the two conformations.

Examine the chair conformations A-F for the structure on the left. The two correct conformations of the hydrocarbon shown in the line and wedge form are compound ________________ and compound ________________. Of the two compounds you identified, compound ________________ is more stable.

Draw the two chair conformations of the compound and circle the more stable conformation. Be sure to draw this compound and not its enantiomer.

Which one of these molecules can readily undergo the chair-to-chair interconversion ("chair flip")?

Draw the most stable chair conformation of each of the following alcohols. (a) (b)

Complete the following reaction by giving the structure of the missing organic starting material.

Complete the reaction by giving the structures of the missing organic products. (Ignore by-products.) (Note that D = deuterium, an isotope of hydrogen, that reacts like hydrogen.)

On the template, complete the other chair conformation of cis-1,3-dimethylcyclohexane and circle the more stable conformation.

Fill in the chair template to show the ring flipped conformation of the structure on the left, numbering the carbons in the ring clockwise from the carbon labeled "1" (include hydrogens). Then circle the conformation that is the more stable.

The two conformations of the hydrocarbon given in planar form at the left are compound ________________ and compound ________________. The more stable conformation of these two is compound ________________.

Select the bridged bicyclic compound with the formula C8H12 that violates Bredt's rule.

Which one of these structures is a properly drawn chair conformation of trans-1,2-dimethylcyclohexane?

Chemical Bonding and Chemical Structure

Alkanes and Organic Nomenclature

The Curved-Arrow Notation, Resonance, Acids and Bases, and Chemical Equilibrium

Introduction to Alkenes and Alkynes

Addition Reactions of Alkenes and Alkynes

Principles of Stereochemistry

Nomenclature and Noncovalent Intermolecular Interactions

The Chemistry of Alkyl Halides

Free-Radical Reactions, Main-Group Organometallic Compounds, and Carbenes

The Chemistry of Alcohols and Thiols

The Chemistry of Ethers, Epoxides, Glycols, and Sulfides

Introduction to Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Dienes and Aromaticity

The Chemistry of Benzene and Its Derivatives

Allylic and Benzylic Reactivity

The Chemistry of Aryl Halides, Vinylic Halides, and Phenols

The Chemistry of Aldehydes and Ketones

The Chemistry of Carboxylic Acids

The Chemistry of Carboxylic Acid Derivatives

The Chemistry of Enolate Ions, Enols, and Α,β-Unsaturated Carbonyl Compounds

The Chemistry of Amines

Carbohydrates

The Chemistry of Thioesters, Phosphate Esters, and Phosphate Anhydrides

The Chemistry of the Aromatic Heterocycles and Nucleic Acids

Amino Acids, Peptides, and Proteins

Pericyclic Reactions

Filters

Examine the chair conformations A-F for the structure on the left. The two correct conformations of the hydrocarbon shown in the line and wedge form are compound and compound . Of the two compounds you identified, compound is more stable.

The two conformations of the hydrocarbon given in planar form at the left are compound and compound . The more stable conformation of these two is compound .

Select the bridged bicyclic compound with the formula C₈H₁₂ that violates Bredt's rule.