Page 269 - Advanced Organic Chemistry Part B - Reactions & Synthesis

Scheme 3.3. Cleavage of Ethers and Esters 241

1 a SECTION 3.3
CH O OCH 3 HO OH Cleavage of
3
H O
BBr 3 2 Carbon-Oxygen Bonds
– 78°C in Ethers and Esters
2 b 75 – 85%
CH OCH 3 CH CH 2
2
CH 2 CH BBr 3 , 2 O
CH Cl
2
O CCH –78°C
CH 3 2 2 O
H H 88%
3 c OH OH
HBr
CH O CH O HOAc HO CH O
3
85°C
18 h 82%
Br Br
200 kg scale
4 d
) SiI
(CH 3 3
OCH 3 OH
83–89%
5 e
(CH ) SiCl
3 3
3 3
3
CO CH 3 CO Si(CH ) + CH I
2
2
Nal, CH 3 CN
86%
6 f
OCH 3 OCH
OCH 3 (CH ) SiI H O 3 OH
2
3 3
CH 3
7 g CH 3
BF 3 CH OH
CH 3 O CH Ph 3
2
C H SH 90%
2 5
Br
8 h Br
OCH 3 OH
H C H C
3
3
BF3
C H SH
H 2 5 H
75%
H H
CH 3 CH 3 CH 3 CH 3
9 i OH OH
CH 3 CH 3
.
BF OEt ,
CH 3 3 2 CH 3
EtSH
CH CH
PhCH O 3 NaOAc HO 3
2
2
H 2 C H C 61%
10 j
O
(CH ) BBr
3 2
Br OH
85%
11 k
FeCl 3
3 2
(CH ) CHOCH(CH ) (CH CO) O (CH ) CHO CCH 3 83%
2
3 2
3 2
3
2
(Continued)