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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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R1 − −<br />

R<br />

N<br />

O<br />

1-CH2-NH-R2 2<br />

BF4 O<br />

N<br />

H R<br />

23<br />

2<br />

+ +<br />

+ + 2<br />

R 1 = Ph, R 2 = Bn; R 1 = i Pr, R 2 = t Bu; R 1 + R 2 = -(CH2)2O(CH2)2-<br />

RO<br />

N<br />

H<br />

t-BOCHN<br />

NH<br />

25<br />

OR1<br />

24<br />

27 29<br />

N<br />

Scheme 2.10<br />

O<br />

2 S<br />

O<br />

24<br />

O<br />

N C<br />

2 S H<br />

OR<br />

+<br />

RO<br />

24<br />

N<br />

O<br />

+<br />

−<br />

O<br />

OR 1<br />

t-BOCHN<br />

O<br />

N<br />

SYNTHESIS OF NITRONES 137<br />

H<br />

O O<br />

28 30 31<br />

Scheme 2.11<br />

N<br />

H<br />

OR<br />

t-BOCHN<br />

C - Phenyl -N -phenylsulfonyloxazirid<strong>in</strong>e (24) (Davis reagent) is also used as<br />

an oxazirid<strong>in</strong>e type oxidant. The use of this reagent <strong>in</strong> oxidations of diazep<strong>in</strong>e<br />

derivatives (25), piperid<strong>in</strong>e (27: R <strong>and</strong> R 1 = Bz or TBDMS), <strong>and</strong> pyrrolid<strong>in</strong>e (28:<br />

R = Bz or TBDMS) gives the correspond<strong>in</strong>g nitrones (26), (29), (30), <strong>and</strong> (31)<br />

<strong>in</strong> quantitative yields (Scheme 2.11) (80–82).<br />

+<br />

−<br />

+<br />

+<br />

N<br />

+<br />

26<br />

N<br />

+<br />

O<br />

−<br />

N<br />

−<br />

+<br />

OR<br />

BF4<br />

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