can be made in principle following the same route starting with other naked sugars
than (À)-172 and (+)-170. Furthermore, intermediate 3-endo-alkylketone 252 can
be equilibrated with the more stable 3-exo-alkylketone under basic conditions.
O
NC
OR*
O
O
OR*
OH
O
O
OMOM
OMOM
O
O
OMOM
OMOM
O
O
O
OMOM
OMOM
O
O
SePh
Cl
LiO
H
Cl
O
O
OMOM
OMOM
O
O
SePh
O
H
H
O
O
OMOM
OMOM
O
H
H
Cl
OMOM
O
OMOM
H
OMOM
O
OMOM
TBSO
O
Cl
BnOOC
OMOM
TBSO
O
OAc
O
O
OMOM
H
BnOOC
OMOM
TBSO
OMOM
OAc
O
O
O
OMOM
OMOM
O
H
N
H
BnOOC
H
BnOOC
OMOM
OAc
O
OMOM
OMOM
TBSO
O
O
O
HO
H
OAc
O
O
O
OMOM
OMOM
O
H 2 N
OMOM
O
O
O
O
PhSe
Cl
CHCl 3
O
O
PhSe
Cl
CH 2 Cl 2
CH 2 Cl 2
Cl
OAc
O
O
O
H
OMOM
N
OMOM
OMOM
OH
O
H
OMOM
OAc
O
O
HN
OMOM
OMOM
OH
N
OH
COOMe
HO
OMe
OH
O
OHHO
H H
OH
OH
N
O
OH
OHHO
HO
OMe
H
(-)-172
(+)-246
PhSeCl
1) (Me 3 Si) 2 NK
THF, - 78
o
C
2) CH 2 =NMe 2 I
(-)-247
(+)-170
1) mCPBA
2) HClO 4 /H 2 O
3) (CF 3 ) 2 CHOH
71%
R* = (1S)-camphanoyl
248
249
1) (MeO) 2 CH 2
P 2 O 5
2) MeOH/DBU
3) (MeO) 2 CH 2
P 2 O 5
80%
+ R*OH
mCPBA
NaHCO 3
90%
250
1) (Me 3 Si) 2 NLi
THF, - 78
o
C
2) + (-)-247
251
AcOH
MeOH
THF
- 78
o
C
90%
252
1) NaBH 4
2) mCPBA
3) MeOCH 2 Cl
(i Pr) 2 NEt
70%
253
1) BnOLi
THF
2) TBSOTf
2,6-lutidine
75%
254
255
1) Me 3 NO
OsO 4 (cat.)
2) Ac 2 O/Et 3 N
DMAP
97%
259
MeOH
SOCl 2
quant.
261
(-)-262
mCPBA
NaHCO 3
80%
256
1) H 2 , Pd/C
2) (PhO) 2 PON 3
3) BnOH
85%
257
1) HF/Py
2) H 2, Pd/C
80%
258
260
1) NaBH 4
HCl/EtOH
H 2 O
2) Dowex
1x8 (OH
- )
61%
80%
84%
Scheme 42 Synthesis of an aza-C-disaccharide
Synthesis of 7-Oxabicyclo[2.2.1]heptane and Derivatives
181