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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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538 NITRONATES<br />

MeO2C<br />

BzO 2C<br />

MeO2C<br />

R 2<br />

HO<br />

R 1<br />

O N<br />

R<br />

R<br />

R<br />

CHClNO2<br />

O<br />

CO2Me<br />

O N O<br />

CO 2Bz<br />

O N O<br />

20°C<br />

slowly<br />

Bu n NH2<br />

H 2; 5% Pd / C<br />

20°C, 1 atm<br />

BuHNOC<br />

HO 2C<br />

O N<br />

R<br />

COCl<br />

O<br />

NH 3<br />

O N<br />

CONH2<br />

O<br />

(1)<br />

O N CONHBu<br />

R alkyl, 2,5-dimethyl-hept-5-ene-yl<br />

O<br />

(2)<br />

7%–55%<br />

O N O<br />

142 143<br />

CO 2Me<br />

O N O<br />

144<br />

O N O<br />

145<br />

CO2R<br />

ClR 2Si<br />

NaBH4 / CH2Cl2<br />

acetonitrile,<br />

R CO2H• O O<br />

Scheme 3.119<br />

HO2C<br />

R2Si<br />

R 2<br />

R 1<br />

O<br />

R<br />

97%<br />

CO 2Me<br />

O N O<br />

73%–75%<br />

CO 2R<br />

O N O<br />

146<br />

Scheme 3.120<br />

~90%<br />

R<br />

R<br />

aryl, But Ref.8<br />

N<br />

H<br />

(3)<br />

(1)<br />

R1 = H, R2 - anti-PhCHOH<br />

R1 = anti-PhCHOH, R2 - H<br />

R1 = Ph, R2 = Me<br />

R1 – n-C12H25, R2 - H<br />

R1 + R2 (2)<br />

- (CH2) 5<br />

R = Me or Et<br />

latter can be considered as efÞcient <strong>in</strong>termediates for <strong>in</strong>tramolecular [3 + 2]-cycloaddition<br />

reactions (66).<br />

3.4.2.5.6. Rearrangements of Cyclic <strong>Nitronates</strong> Many rearrangements of cyclic<br />

nitronates occur under the action of LA <strong>and</strong> <strong>in</strong>volve the <strong>in</strong>teraction with the<br />

negative end of the dipole as the <strong>in</strong>itial step. If an aryl substituent is bound to<br />

the C-4 atom, deep skeletal rearrangements, <strong>in</strong>clud<strong>in</strong>g annelation, are possible.<br />

Japanese researchers (321) systematically studied the reactions of a representative

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