Mechanisms Flashcards
Reagents: HX
HydroHalide Addition to Pi Bond
- Markovnikov Regiochemistry
- Carbocation Rearrangement
Reagents: Weak Nucleophile, Strong Acid Catalyst (Typically H2O, H3O+)
Acid-Catalyzed Hydration of Pi Bond - Markovnikov Regiochemistry - Carbocation Rearrangement
Reagents: 1) Hg(OAc)2, HOH, THF
2) NaBH4
Oxymercuration / Demercuration
- Markovnikov Regiochemistry
- Anti/Trans Stereochemistry
- No Carbocation Rearrangement
Reagents: 1) Hg(OAc)2, HOR, THF
2) NaBH4
Alkoxymercuration / Demercuration
- Markovnikov Regiochemistry
- Anti/Trans Stereochemistry
- No Carbocation Rearrangement
Reagents: 1) BH3, THF
2) H2O2, NaOH, H2O
Hydroboration Oxidation
- Anti-Markovnikov Regiochemistry
- Syn / Cis Stereochemistry
- Carbocation Rearrangement
Reagents: HX, ROOR (peroxides), heat or light
Anti-Mark HydroHalide Addition to Pi Bond
- Anti-Markovnikov Regiochemistry
- Carbocation Rearrangement
Reagents: Br2 or Br2, HOR
Electrophilic Addition of Br2 to Pi Bond (Bromonium Ion)
- Markovnikov Regiochemistry
- Anti / Trans Stereochemistry
- No Carbocation Rearrangement
Reagents: Peroxy Acid (ROOOH) (Typically MCPBA)
Epoxide Ring Formation
Reagents: 1) MCPBA
2) H+, HOR
Epoxide Ring Opening (Acidic Conditions)
- Markovnikov Regiochemistry (follows the carbocation)
- Anti / Trans Stereochemistry
- No Carbocation Rearrangement
- Can Add 2 OH or 1 OH & 1 OR Group
Reagents: 1) MCPBA
2) Strong Base (HOR, NR2-, NaR)
3) Dilute Acid or RX
Epoxide Ring Opening (Basic Conditions)
- Anti-Markovnikov Regiochemistry (goes for spot with less steric hindrance)
- Anti / Trans Stereochemistry
- Can Add 2 OH, 2 OR, or 1 OH & 1 OR Group
Reagents: CHCl3, KOH or CH2I2, Zn(Cu)
Cyclopropane Ring from a Pi Bond
- Carbene addition to the pi bond
- Carbenes need to be made in situ
Reagents: H2, Pt or Pd metal
Strongly Catalyzed Reduction of Pi Bonds
- Syn / Cis Stereochemistry
- Reduces all Pi Bonds in Alkenes and Alkynes
Reagents: H2, Ni2B or H2, Lindlar Catalyst
Weakly Catalyzed Reduction of Pi bonds
- Syn / Cis Stereochemistry
- Only Reduces first Pi Bond in Alkenes and Alkynes
Reagents: Na metal, NH3 liquid
Weakly Catalyzed Reduction of Pi Bonds
- Anti / Trans Stereochemistry
- Only Reduces first Pi Bond in Alkenes and Alkynes
Reagents: PCC
Oxidation of Primary Alcohol to Aldehyde
- Removes two H’s to form double bond across C-O
- Weaker oxidizing agent