Chemistry Reference
In-Depth Information
R
2
O
H
Li
O
H
Me
I
+
Me
O
Me
NaHCO
3
MeCN, N
2
LiBr, N
2
THF, - 78 °C
R
Me
R
-H
+
Me
SH
SH
Me
SH
65
Yields (%)
R
65 66
Ph 90 71
thien-2-yl 91 65
n
-Bu
OH
I
Me
I
Me
Me
R
Me
R
S
-H
2
O
S
85 67
Bn
51 68
66
Scheme 93 Iodine-promoted closure of a 1-mercapto-3-yn-2-ol to a 3-iodothiophene [
139
]
Me
Me
Me
CuCl, DBU
PhMe, 50 °C
R
PhO
2
S
PhO
2
S
S
+
H
R
PhO
2
S
R
SH
S
67
68
69
R
yield (%)
Ph
91
thien-2-yl
68
pyridin-2-yl
85
n
-Bu 91
CH
2
OCOCH
2
Cl 75
Scheme 94 Copper-promoted closure of a 1-mercapto-3-yne intermediate [
140
]
H
H
H
H
O
NaH, THF, reflux
then
m
-CPBA, CH
2
Cl
2
91%
BnBr, THF, reflu
x
95%
HO
OH
BnO
OBn
BnO
OBn
·
HO(CH
2
)
2
Br
BF
3
MsCl, Et
3
N
CH
2
Cl
2
,0°C
9H
2
O
DMF, 50 °C
78%
Na
2
S
H
2
,Pd/C
EtOH, HCl (ca
t)
96%
KOH
EtOH, reflux
O
O
O
O
·
OEt
2
,CH
2
Cl
2
92%
67%
MsO
OMs
BnO
OBn
O
O
O
O
DDQ, PhCl, 80 °C
21%
S
S
70
EDOT
Scheme 95 Transformation of (
Z
)-but-2-ene-1,4-diol into EDOT [
141
]
69. Thus, reaction with terminal alkynes under copper catalysis generates the thiol
intermediate 68 (Scheme
94
)[
140
].
2.8.5 From (Z)-But-2-Ene-1,4-Diol
In a single example of the use of this starting material, EDOT was produced and
en
route
various chiral intermediates [
141
]. The commercially available diol was first
O
-protected and then epoxidised and the epoxide taken through some standard
transformations ending with tetrahydro-EDOT, 70, which was aromatised using
DDQ (Scheme
95
).
