Organic Chemistry

Therefore, the required reactants for (a) are:

By cutting through (b), we can determine the required reactants for its synthesis:

Therefore, the required reactants for (b) are:

Now continue on to Problem 33.

PROBLEM 33

Propose a synthesis for each of the following compounds, using a Robinson annulation:

19.17 Decarboxylation of 3-Oxocarboxylic Acids

Carboxylate ions do not lose , for the same reason that alkanes such as ethane do

not lose a proton—because the leaving group would be a carbanion. Carbanions are

very strong bases and therefore are very poor leaving groups.

CO 2

O

CH 3

O

H 3 C

b. d.

O

CH 3

c.

H 3 C

C 6 H 5

O

O CH 3

a.

CH 2 CH 3

HO−

∆

O

CH 2 CHCCH 3

O

+ CH 3 CCH 3

CH 3

O

CH (^3) CH 3
O
O
O
CH 3
O
HO−
∆
O
CH 2 CHCCH 3 + CH 3 CH 2 CH
O
, -unsaturated
carbonyl compound
CH 3 CH^3
CH
O
O O CH 3
818 CHAPTER 19 Carbonyl Compounds III