Reaction tools & tips

Question 1

Hydroboration
Regiochemistry?
Stereochemistry?

Answer 1

Regiochem: anti-mark
sterochem: syn

BH3/THF or B2H6

reaction is anti-mark because of the H-B bond the H adds to the carbon best able to stabilize the carbon which is most substituted.

Question 2

Oxymercuration
Regiochemistry?
Stereochemistry?

Answer 2

Regiochem: Mark
Stereochem: syn + anti

3 membered mercurium bridged ion, the NaBH4 removes the Hg, the addition is anti

Question 3

Acid-Catalyzed Hyrdation of H20
Regiochemistry?
Stereochemistry?

Answer 3

regiochem: Mark
stereochem: syn + anti

a strong acid protonates the strong alkene generating a carbocation and watch out for the possibility of a rearrangement

Question 4

Addition of HX

Answer 4

regiochem: mark
stereochem: syn + anti

HCL, HBR (HI) protonate the alkene to give a carbocation which gets attacked by the nucleophile

Question 5

DIhydroxaltion

Regiochemistry?
Stereochemistry?

Answer 5

stereochem: Syn

this rxn makes a diol, two OH’s bonded on two different carbons.

OsO4

KMnO4 in cold dilute/water

But if heat and acid is present you will get carbonyl compounds as present with the reactions just as ozonolysis

anti-hydroxylation can be achieved through epoxidation followed by treatment with NaOH or H30+

Question 6

Epoxidation
Regiochemistry?
Stereochemistry?

Answer 6

stereochem: Syn
RCO3H peroxy acid
McPBA
if H30+ ,Heat you get the opening of the epoxide with anti addition of diols

Question 7

Hydrogenation
Regiochemistry?
Stereochemistry?

Answer 7

stereochem: syn

H2/Pd,Pt, Ni

Question 8

Radical Addition to HBr
Regiochemistry?
Stereochemistry?

Answer 8

regiochem: anti-mark
stereochem: syn + anti
peroxide is the hint to look for so you know its anti