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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 />

X<br />

X<br />

X<br />

X<br />

S<br />

208<br />

D<br />

F<br />

E<br />

SiMe3<br />

NO 2<br />

O<br />

LA<br />

OH<br />

OH<br />

NO 2<br />

N<br />

OH<br />

O<br />

80%–90%<br />

N<br />

O<br />

N<br />

O<br />

H<br />

OTMS<br />

O<br />

N<br />

OSiMe3<br />

LA, CH 2Cl 2<br />

−10°−0°<br />

R = SiMe3; X = H; 5-Br; 5-OMe; 7-OMe;<br />

LA – AlCl 3, TiCl4, BF3⋅OEt2, SnCl4.<br />

Me 3SiCH 2MgCl<br />

BF3⋅OEt2<br />

−78°→−40°, CH2Cl 2<br />

Scheme 3.147<br />

O<br />

209<br />

S<br />

CH 2<br />

REACTIVITY OF NITRONATES 567<br />

X<br />

X<br />

X<br />

X<br />

NO2<br />

H CH2 SiMe3<br />

O<br />

OH<br />

Scheme 3.148<br />

SiMe 3<br />

O<br />

207<br />

C<br />

O<br />

O<br />

O<br />

BF 3⋅OEt 2<br />

−20°C, CH 2Cl 2<br />

A<br />

H<br />

R<br />

O<br />

N<br />

O<br />

O LA<br />

N<br />

OSiMe3 −<br />

O<br />

N<br />

LA<br />

O<br />

LA<br />

N<br />

~90% dr ~ 10:1<br />

OSiMe 3<br />

B<br />

OSiMe3<br />

S<br />

210<br />

N<br />

OH<br />

61%

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