Chemistry Reference
In-Depth Information
affords unsymmetrical product as a single diastereisomer [81a] (Scheme 4.31a). Formyl-
methyl-substituted pyranoses react with phosphorylglycinate at lower temperature (
78
C)
in the presence of TMG (1) to give products in satisfactory yields [81b] (Scheme 4.31b).
Barrett et al. [82] prepared high-loading polymer phosphonate resins, a related resin used
in oxazole formation (Oxazolidinone and Oxazole), by polymerization, which in combi-
O
(EtO)
2
P
CO
2
Me
NHCbz
CbzHN
(a)
MeO
2
C
CHO
OHC
CHO
TMG (
1
) / DCM
10 min, rt
94%
O
(MeO)
2
P
CO
2
TMSE
TMG (
1
) / DCM
24 h, rt
NHBoc
CbzHN
NHBoc
MeO
2
C
CO
2
TMSE
83%
TMSE = Me
3
Si(CH
2
)
2
O
(MeO)
2
P
CO
2
Me
R
4
OAc
R
4
OAc
R
2
R
2
NHCbz
O
R
3
O
R
3
(b)
AcO
NHCbz
AcO
R
1
TMG (
1
)
1 h, -78 ºC
R
1
CO
2
Me
CHO
R
1
R
2
R
4
yield
(%)
R
3
79
OAc
H
H
OAc
85
OAc
H
OAc
H
88
H
OAc
OAc
H
Scheme 4.31
Examples of TMG (1) mediated HWE reactions
