Exam 5 Flashcards
Diene
two Alkenes in close proximity
Cumulated Diene
the double bonds are linked
Conjugated Diene
the double bonds are separated by a single bond
- has both sp2 and sp3 character
- can form resonance
Diene Stability
- Trans conformation is more stable
- Cis conformation (half a ring) is less stable
- More substituted double bond is chosen
1,2- Addition
- Concerted
- Kinetic product
1,4- Addition
- Requires an addition of heat
- Thermodynamic product
- Reaction must be reversible
H-X, -80ºC
1,2- kinetic product
H-X, 40ºC
1,4- thermodynamic product
- Resonance
Diels-Alder
- Cis Diene and a dienophile make a ring
- Must match the partial negative and partial positive
- Must be 1,2 or 1,4 product for the EDG/EWG
Stereochemistry:
- Reacts to form the endo product, EWG is under the diene when it reacts
- Anything pointing to the right is up
Diene
- can be a chain or an open ring
- Must be able to adapt
- Electron donating group (EDG) makes a partial negative
- when flipping the chain into the ring the substituents rotate on the single bond
Dienophile
- a double bond with substituents
- Electron withdrawing group (EWG) makes a partial positive
Synthesis of Alcohol: Substitution
SN2: NaOH -> -OH
SN1: H2O
Synthesis of Alcohol: Alkenes
Mark Addition
A. H2SO4, H2O
B. 1. Hg(AOC)2, H2O
2. NaBH4
Anti-mark Addition (Syn)
C. 1. BH3, THF
2. H2O2, NaOH
Synthesis of Alcohol: Alkene -> Diols (two OH groups)
Syn:
A. 1. KMnO4 (Cold)
2. H2O
B. OsO4, H2O2
Trans:
C. 1. mCPBA
2. H2SO4. H2O
:H- Nucleophile
- NaBH4
- LiAlH4
- Reacts with an acid
NaBH4
- Weaker
- Reacts with only ketones and aldehydes
LiAlH4
- Stronger
- Reacts with all carbonyl functional groups
Reduction of Esters with :H- and an acid
adds two :H-
1. :H- reduces the double bonded O
2. Resonance reforms the double bond and pushes off the O group
3. a second :H- attacks
Carbon Nucleophiles
R-MgBr
R-Li
R2-CuLi
- Reacts with an acid
-Adds the carbon chain to reduce the ketone/aldehyde to an alcohol
- Adds the carbon chain twice to reduce the ester to an alcohol
R-MgBr
- Grignard Reagent
- can react with alkyl halide to make a longer carbon chain and MgBr2
Synthesis of ethers: General
- NaO-R -> -:O-R
- R-OH
Synthesis of ethers: Williamson Ether (SN2)
- NaH
- R-Br
Synthesis of ethers: Acid Catalyzed
H2SO4, CH3OH
Synthesis of ethers: Oxymercuration
- Hg(OAC)2, R-OH
- NaBH3
Reactions of Ethers
- Strong Acid (H-X)
1º/2º:
1. O lone pair attacks the H
2. -:X attacks less substituted carbon and gives the electrons to the positive oxygen
3º:
1. O lone pair attacks the H
2. tertiary carbon willingly gives the positive oxygen the electrons in the bond
3. -:X attacks the tertiary carbocation
Epoxide Opening to an Ether w/ Acid
H2SO4, R-OH
1. Acid gives the epoxide a hydrogen
2. the R-OH uses its lone pair to attack the more substituted side and opens the epoxide ring
Epoxide Opening to an Ether w/ Base
-:O-R, R-OH
1. -:O-R attacks the less substituted side of the epoxide ring opening it
2. a lone pair on the -:O from the newly open epoxide ring takes an H from the R-OH in solution
Epoxide Opening to an Ether w/ a carbon nucleophile
Carbon Nucleophile + Acid
- attacks less substituted side of the epoxide ring
Thiol
CH3-S-H
- More acidic than alcohol
Thioether
CH3-S-CH3
- Better nucleophile than Ether
