Oxymercuration(1) C Reagent is mercury (I) acetate which dissociates slightly to form *Hg(oac *Hgoac)is the electrophile that attacks the pi bond 十 CH3-C-0-Hg-0-C-CH3 -CH3-C-0 Hg-0-C-CH3 = hapter 8 16
Chapter 8 16 Oxymercuration (1) • Reagent is mercury(II) acetate which dissociates slightly to form +Hg(OAc). • +Hg(OAc) is the electrophile that attacks the pi bond. CH3 C O O Hg O C O CH3 CH3 C O O _ Hg O C O CH3 + =>
Oxymercuration(2) C The intermediate is a cyclic mercurinium ion, a three-membered ring with a positive charge OAc Hoac Chapter 8 17
Chapter 8 17 Oxymercuration (2) The intermediate is a cyclic mercurinium ion, a three-membered ring with a positive charge. C C + Hg(OAc) C C Hg + OAc =>
Oxymercuration (3) C Water approaches the mercurinium ion from the side opposite the ring(anti addition) Water adds to the more substituted carbon to form the Markovnikov product OAc OAc OAc He g -C-C Ho H H2O- hapter 8 18
Chapter 8 18 Oxymercuration (3) • Water approaches the mercurinium ion from the side opposite the ring (anti addition). • Water adds to the more substituted carbon to form the Markovnikov product. C C Hg + OAc H2O C O + C Hg H H OAc H2O C O C Hg H OAc =>
Demercuration C Sodium borohydride, a reducing agent replaces the mercury with hydrogen OAc Hg H Nabh t 4 oh 4—C—C Nab(Oh) t 4 Hgt 4 oac Chapter 8 19
Chapter 8 19 Demercuration Sodium borohydride, a reducing agent, replaces the mercury with hydrogen. C O C Hg H OAc 4 4 C O C H H + NaBH4 + 4 OH _ + NaB(OH)4 + 4 Hg + 4 OAc _ =>
Predict the product C Predict the product when the given alkene reacts with aqueous mercuric acetate followed by reduction with sodium borohydride CH OH (1)Hg(oAc)2, H2O CH3 D (2) NabH4 anti addition Chapter 8 20
Chapter 8 20 Predict the Product Predict the product when the given alkene reacts with aqueous mercuric acetate, followed by reduction with sodium borohydride. CH3 D (1) Hg(OAc) 2, H2O (2) NaBH4 => OH CH3 D H anti addition