Synthesis of Cylindrospermopsin

C15H21N5O7S
Principal investigator | Barry B. Snider |
---|---|
Publication year | 2000 |
Synthesis type | Total |
Number of steps | 24 (3 parts) |
References |
Part 1 of 3

POCl3,
PCl5
Reflux, 2 d

MeOH
0 °C to RT, 12 h, 57% (2 steps)

LiBH4
EtOH, THF
RT, 2 h, 93%


Part 2 of 3
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ClCO2CH2CCl3
THF
-30 °C, 2.5 h, 49%
"The yield was 87 % brsm."


Zn
AcOH, CH2Cl2
RT, 5 h, 96%

Li(s-Bu)3BH
THF
-78 °C, 2 h, 94%

ClCO2Bn,
Na2CO3
THF
RT, ON, 96%

Imidazole,
DMAP,
TBSCl
CH2Cl2
RT, ON, 89%

Part 3 of 3
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Imidazole,
TBSCl
CH2Cl2
RT, 5 h, 88%

- O3
- Me2S
CH2Cl2
-78 °C, 20 min, 72%

BnNH2,
Na2SO4,
NaBH3CN
AcOH, MeOH, PhMe
RT, 4 h, 68%

H2,
Pd/C
1 atm
MeOH
RT, ON

BrCN
PhMe
RT, 5 h

ClCO2Bn,
NaH
THF
0 °C to RT, 8 h, 45% (3 steps)

n-Bu4N+ F-
THF
RT, ON, 83%

MnO2
CH2Cl2
RT, 60 min, 87%

Ac2O
Pyr
RT, ON, 87%


CuBr2
EtOAc
35 °C, 20 min

H2,
Pd(OH)2/C
1 atm
MeOH
RT, 8 h, 42% (2 steps)
"Also isolated was the C7-epimer (28 % yield)."

HCl
H2O
100 °C, 6 h, 95%

Na2SO4,
SO3.DMF
Pyr
RT, ON, 50-70%
