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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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ArCNO + 359<br />

CH2Cl<br />

OMe<br />

Ar<br />

ArCNO, BF3<br />

+<br />

N O R′<br />

363<br />

Ar<br />

R<br />

(a)<br />

Cl −<br />

Ar<br />

Ar<br />

(b)<br />

(c)<br />

REACTIONS OF NITRILE OXIDES 77<br />

N O R′<br />

Ar<br />

Cl<br />

364<br />

R<br />

N O R′<br />

N O R′<br />

367<br />

Scheme 1.40<br />

N CH2Cl<br />

OH<br />

OMe<br />

−78 °C,<br />

CH2Cl2 +<br />

Scheme 1.41<br />

+<br />

R<br />

R<br />

Ar<br />

365 366<br />

Ar<br />

Ph<br />

+<br />

N O R′<br />

H2O<br />

361<br />

+<br />

362<br />

+<br />

RCOR′<br />

N OMe<br />

OH<br />

R<br />

CH2Cl<br />

Reactions of 2-nitrosopyrid<strong>in</strong>e with nitrile oxides afford, depend<strong>in</strong>g on structure<br />

of the latter, either 1,2,4-triazolo[1,5-a]pyrid<strong>in</strong>e 1,3-di-N-oxides (370) orthe<br />

correspond<strong>in</strong>g 1,2,4-triazolo[1,5-a]pyrid<strong>in</strong>e 3-oxides (371) (419).<br />

O<br />

N<br />

N<br />

370<br />

N<br />

R<br />

O<br />

R = 2,6-Cl 2C 6H 3, 4-O 2NC 6H 4; R 1 = 2,4,6,-Me 3C 6H 2, Ph, 4-MeC 6H 4, 4-ClC 6H 4<br />

O<br />

N<br />

N<br />

371<br />

N<br />

R 1

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