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Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis : Novel ...

Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis : Novel ...

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O<br />

O<br />

O<br />

N<br />

Pri OCOPh<br />

R<br />

Me<br />

Bn<br />

CO 2H<br />

NHCbz<br />

S R<br />

N<br />

399 a<br />

Ph<br />

S<br />

Ph<br />

a,b<br />

Me<br />

(−)−<br />

c-e<br />

O<br />

M<br />

O<br />

403a<br />

anti<br />

Me<br />

O<br />

N<br />

Pri S<br />

399<br />

−<br />

Bn<br />

N<br />

OCOPh<br />

Cl<br />

Ph<br />

400<br />

a: CH2Cl2,−78°C b: SiO2 column<br />

c: H2, Pd/C, AcOH<br />

d: CbzCl, K2CO3 e: LiOH, H2O2 + − + −<br />

PhCOCl<br />

Bn<br />

N<br />

O<br />

CH2CH2, −78°C<br />

O<br />

N<br />

Pri OCOPh<br />

R<br />

Me<br />

Ph<br />

Bn<br />

CO 2H<br />

NHCbz<br />

S R<br />

O<br />

N<br />

M = BEt 2(a), TiCl 2 O-Pr i (b)<br />

Ph<br />

O<br />

R<br />

Ph<br />

399b<br />

Me<br />

(+)− 403b<br />

c-e<br />

a,b<br />

syn<br />

Et2<br />

B<br />

O<br />

O<br />

O<br />

O<br />

N<br />

Pri OCOPh<br />

N<br />

S<br />

R<br />

Me<br />

anti<br />

Bn<br />

NHCbz<br />

CO<br />

R<br />

2H<br />

Me<br />

403a<br />

S<br />

(+)−<br />

a,b<br />

O<br />

Me<br />

92%<br />

97% de<br />

Ph<br />

c-g<br />

Ph<br />

NITRONE REACTIONS 277<br />

N O<br />

R<br />

Me Ph<br />

401<br />

Cl2OPr O O<br />

i<br />

Ti<br />

Ph<br />

Bn<br />

N O<br />

O<br />

OCOPh<br />

N O<br />

S N<br />

Me<br />

S<br />

Bn<br />

Ph<br />

Me<br />

a: PhCOOCl<br />

b: 401 toluene<br />

c: SiO2 column<br />

d: Zn, AcOH<br />

e: LiOH, H2O<br />

f: H2, Pd/C<br />

g: CbzCl, K2CO3 h: 402 CH2Cl2 i: LiOH, H2O2 −<br />

+<br />

N<br />

S<br />

N<br />

CO2Me<br />

402<br />

NHCbz<br />

CO<br />

S<br />

2H<br />

Me<br />

403b<br />

S<br />

(−)−<br />

Ph<br />

c,f,g,i<br />

Ph<br />

a,h<br />

N<br />

CO2Me<br />

Bu t<br />

79%<br />

96% de<br />

Bu t<br />

syn<br />

Scheme 2.179

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