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

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524 NITRONATES<br />

SiO<br />

N<br />

O<br />

O<br />

MeO<br />

SAr<br />

Cl<br />

LiClO4<br />

−LiCl<br />

Ar<br />

S<br />

OMe<br />

117b<br />

OMe<br />

SHAr<br />

MCl 5 −<br />

117c<br />

SHAr<br />

O ClO −<br />

4<br />

117a<br />

TiCl 5 −<br />

SiO Ar<br />

R 1<br />

N<br />

R 2<br />

O<br />

Ar = m-ClC 6H6<br />

Si – SiMe3.<br />

R1 70%–100%<br />

O<br />

Me<br />

ArS<br />

O<br />

MeO<br />

SAr<br />

O<br />

N<br />

OSi<br />

Cl<br />

H<br />

O<br />

N<br />

Cl<br />

Et<br />

MeO<br />

MeO O<br />

N<br />

ArS 46%<br />

Scheme 3.96<br />

O O H<br />

0°, CH 2Cl 2, 0.5 h<br />

O<br />

R 2<br />

Ar<br />

−HNO2<br />

Scheme 3.97<br />

− Ar<br />

O<br />

Si<br />

O O<br />

O<br />

H<br />

OSi<br />

R 1<br />

−SiOH<br />

O<br />

N<br />

R 1<br />

H<br />

O2N O<br />

R 2<br />

Me<br />

O<br />

45%<br />

Cl<br />

M = Ti, 31%<br />

M = Sn, 18%<br />

Cl<br />

Et<br />

O<br />

R 2<br />

Si – Me 3Si.<br />

It should be noted that this reaction is one of the mildest <strong>and</strong> most convenient<br />

methods of transform<strong>in</strong>g secondary AN <strong>in</strong>to ketones.<br />

SENAs are convenient substrates for radical reactions (Scheme 3.98). This is<br />

due to several factors.<br />

First, SENAs should be rather readily oxidized <strong>in</strong> one-electron transfer reactions.<br />

For example, MeCH=N(O)OSiMe2Bu t gives an oxidation peak <strong>in</strong> the<br />

SAr<br />

O<br />

N

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