09.02.2013 Views

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

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

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

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

R<br />

O N<br />

H<br />

Ar * SeOTF CH 2Cl 2<br />

R<br />

O N<br />

H<br />

115a−d<br />

∗<br />

R 1<br />

SeAr *<br />

+<br />

∗<br />

R 1<br />

a: R = Ph, R 1 = H<br />

b: R = Me, R 1 = H<br />

c: R = Ph, R 1 = Ph<br />

d: R = Me, R 1 = Ph<br />

Me<br />

Me<br />

5-exo<br />

6-endo<br />

6-exo<br />

N<br />

OH<br />

124<br />

N<br />

OH<br />

125<br />

−<br />

O<br />

R<br />

N<br />

O<br />

R<br />

R<br />

N<br />

+<br />

*<br />

Ph<br />

N O<br />

SeAr *<br />

118a−b or 119a−b<br />

−<br />

+<br />

120c−d or 121c−d<br />

*<br />

*<br />

SeAr *<br />

SYNTHESIS OF NITRONES 169<br />

SeAr *<br />

122a−b or 123a−b<br />

Scheme 2.45<br />

AgBF 4<br />

CH 2Cl 2<br />

AgBF 4<br />

CH 2Cl 2<br />

Scheme 2.46<br />

Me<br />

Me<br />

X<br />

N<br />

O<br />

126<br />

N<br />

O<br />

127<br />

SMe<br />

SeOTF<br />

116 X = H<br />

117 X = OMe<br />

+<br />

+<br />

−<br />

−<br />

Ar * Se<br />

Bicyclic nitrones (132) were formed from the reaction of alkenyl carbonyl<br />

compounds (131) with hydroxylam<strong>in</strong>e. The reaction requires the presence of the<br />

term<strong>in</strong>al oleÞnic electron withdraw<strong>in</strong>g ester group CO2Et. Also, the product(s) of<br />

reaction are shown to depend on the space Þll<strong>in</strong>g capacity of substituents R 1 − R 4

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!