04 alkene reagents

Alkene to alkane (syn)

H2, Pd/C (or Pt, Ni)

Alkene to Markovnikov alkyl halide

HX (HCl, HBr, HI)

Alkene to anti-Markovnikov alkyl bromide

HBr, ROOR

Alkene to Markovnikov alcohol (rearrangement possible)

H2O, H2SO4 (H3O+)

Alkene to Markovnikov alcohol, no rearrangement

1) Hg(OAc)2, H2O 2) NaBH4

Alkene to anti-Markovnikov alcohol, syn addition

1) BH3·THF 2) H2O2, NaOH

Alkene to vicinal dibromide (anti)

Br2, CH2Cl2

Alkene to vicinal dichloride (anti)

Cl2, CH2Cl2

Alkene to bromohydrin

Br2, H2O (or NBS, H2O)

Alkene to bromo ether

Br2, ROH

Alkene to epoxide

mCPBA (or another peroxy acid)

Alkene to anti diol

1) mCPBA 2) H3O+

Alkene to syn diol

OsO4, NMO (or cold, dilute KMnO4, NaOH)

Alkene to aldehyde/ketone fragments

1) O3 2) DMS (or Zn, H2O)

Alkene to carboxylic acid/ketone fragments (oxidative)

1) O3 2) H2O2

Alkene to carboxylic acids with hot KMnO4

Hot, concentrated KMnO4 cleaves and oxidizes (RCH= becomes RCOOH)

Which hydration avoids carbocation rearrangement?

Oxymercuration-demercuration (or hydroboration for anti-Markovnikov)

Which reagent gives syn H and OH addition?

Hydroboration-oxidation

Which reagent gives anti addition of two Br?

Br2 in CH2Cl2

Alkane to bromoalkane at 3° C-H

Br2, hv (very selective)

Alkene to allylic bromide

NBS, hv (or ROOR)

Hydrogenation: syn or anti?

Syn (both H add to the same face)

Epoxidation: syn or anti?

Syn (stereospecific; cis alkene gives cis epoxide)

Which reagent for cis diol from cyclohexene?

OsO4/NMO

Which reagent for trans diol from cyclohexene?

1) mCPBA 2) H3O+

Best reagent when a rearrangement-prone alkene needs Markovnikov OH

1) Hg(OAc)2, H2O 2) NaBH4