Specific Reaction Mehanisms

Question 1

Hydroboration

Answer 1

Overall addition of H2O across C=C forming antimarkovnikov product, needs H2O2, NaOH for last step

Question 2

Bis-hydroxylation

Answer 2

Forms cis-1,2-diols using alkene and OsO4, needs NaHSO3/H2O to hydrolyse (OsO4)2- at last step

Question 3

Brominaton

Answer 3

Trans addition

Question 4

Co-halogenation

Answer 4

Forms halohydrin, trans and markovnikov product

Question 5

Oxymercuration

Answer 5

Addition of water across C=C using Hg(OAc)2, markovnikov product with OH on most substituted C, needs NaBH4 to remove HgOAc at last step

Question 6

Epoxidation

Answer 6

Uses m-CPBA with alkene

Question 7

Epoxidation under basic conditions

Answer 7

Nu- attacks less sterically hindered C by Sn2 forming anti-markovnikov product

Question 8

Epoxidation under acidic conditions

Answer 8

Forms anti-1,2-diols, Nu- attacks most stable C forming markovnikov product

Question 9

Leaving group for E2

Answer 9

Must be antiperiplanar/1,2-transdiaxial

Question 10

Leaving group for Sn2

Answer 10

Must be axial

Question 11

Bredt’s rule

Answer 11

Rigid bicyclic ring systems can’t accommodate a double bond at bridgehead positon so no elimination occurs here

Question 12

What does NaIO4 do

Answer 12

Cleaves cyclic 1,2-diols forming a linear aldehyde/ketone with 2 carbonyl groups