Advices For Studying Organic Chemistry

5. Care must be taken in designing syntheses involving Grignard reagents ⇒ the
   reacting electrophile can not contain an acidic group.

1. The following reaction would take place when 4-hydroxy-2-butanone is treated
   with methylmagnesium bromide:

CH 3 MgBr + HOCH 2 CH 2 CCH 3 CH 4 ¡ô

O

+ BrMgOCH 2 CH 2 CCH 3

O

4-Hydroxy-2-butanone

rather than:

CH 3 MgBr

CH 3

+ HOCH 2 CH 2 CCH 3

O

HOCH 2 CH 2 CCH 3

OMgBr

2) Two equivalents of methylmagnesium bromide can be utilized to effect the

following reaction:

HOCH 2 CH 2 CCH 3
O

CH 3 MgBr

CH 4 BrMgOCH

CH 3 CH 3

2

−^2 CH^2 CCH^3

OMgBr

2 NH 4 Cl

H 2 O HOCH^2 CH^2 CCH^3

OH

12.8C THE USE OF LITHIUM REAGENTS

1. Organolithium reagents (Rli) react with carbonyl compounds in the same way as
   Grignard reagents.

+ H^3 O

δ− δ+ +

R Li R R

Alcohol

CO C O C OH

Aldehyde

or

ketone

Li

Organolithium

reagent

Lithium

alkoxide

1) Organolithium reagents are somewhat more reactive than Grignard reagents.

12.8D THE USE OF SODIUM ALKYNIDES