Chemistry Reference
In-Depth Information
O
MeMgBr, THF, 0 °C
then PhCH=CHCOCl,
-78 to 0 °C
Ph
N
N
O
O
OH
OH
O
O
O
O
HO
OH
O
O
Me
Me
D-Xylose
O
O
Me
Me
O
1
2
Ph
N
O
O
Et
2
AlCl, CH
2
Cl
2
,
—80 °C
O
Et
O
Et
O
HCl
O
Me
O
Xc
Ph
(91%)
HO
Ph
Xc
Me
7
4%
de
2
3
4
Scheme 2.1
1,4-Addition of an ethyl nucleophile to d-xylose-derived
N
-cinnamoyl-2-oxazinone
2.
of 3,4,6-tri-
O
-pivaloyl-d-galactal, followed by hydrolysis and oxazoline formation
via a Staudinger-aza-Wittig reaction cascade (Scheme 2.2).
1) NaN
3
,CAN,MeCN
(65%)
2) NaNO
2
, aq. H
2
O
(71%)
MeMgBr,
R
1
CH=CHCOCl
-78 °C
PivO
OPiv
PivO
OPiv
PivO
OPiv
O
O
O
PivO
PivO
PivO
3) PPh
3
,CO
2
,dioxane
(59%)
HN
R
1
N
O
(>90%)
O
3,4,6-Tri-
O
-pivaloyl-
D-galactal
O
R
1
=PhorMe
O
O
5
6
Xc
R
2
2
AlCl, toluene,
LiOH, H
2
O
2
,
THF, H
2
O, 0 °C
Ph
OH
PivO
R
1
Xc
OPiv
O
R
1
R
2
temp.
yield
de
O
Et
O
PivO
R
2
for R
1
=Ph, R
2
=Et
R
1
Ph
Ph
Ph
Ph
Me
Me
Me
Me
Et
Me
Pr
i
-Bu
Et
Pr
Ph
i
-Bu
-78°C
-40°C
-40°C
-40°C
-30°C
-40°C
-40°C
-40°C
84%
82%
74%
87%
70%
38%
56%
70%
96%
>98%
>98%
>98%
80%
>98%
>98%
90%
N
8
(87%)
O
7
+
5
(98%)
O
O
6
R
1
=Ph,Me
Scheme 2.2
Synthesis of d-galactosamine-derived
N
-acylated oxazolidinones
6
and subse-
quent 1,4-additions with various organoaluminum species.
Conversion of
5
into the
N
-acyl derivatives
6
by deprotonation with methylmag-
nesium bromide was followed by treatment with the two
-unsaturated acyl
chlorides. The resulting
N
-acyloxazolidin-2-ones
6,
fused with per-
O
-pivaloylated
α
,
β
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