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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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NH 2<br />

NH 2<br />

Boc<br />

N H2N N(OH)Bn<br />

Boc<br />

N<br />

Ph Ph<br />

iv<br />

Ph<br />

Ph<br />

iii<br />

Ph<br />

Ph<br />

i<br />

O<br />

96%<br />

OH<br />

93%<br />

O<br />

90%<br />

323a<br />

meso-<br />

ds ><br />

−<br />

95%<br />

Boc<br />

N<br />

+<br />

Ph<br />

NBn<br />

O O<br />

NH2 NH2<br />

Ph Ph<br />

Boc<br />

N H2N N(OH)Bn<br />

Boc<br />

N<br />

iv<br />

iii<br />

ii<br />

92%<br />

Ph<br />

Ph<br />

89%<br />

Ph<br />

Ph<br />

97%<br />

63a<br />

OH<br />

O<br />

O<br />

323<br />

(S,S)-<br />

ds = 94%<br />

Boc<br />

N<br />

NITRONE REACTIONS 241<br />

NH 2<br />

Boc<br />

N H2N<br />

N(OH)Bn<br />

NH2<br />

Boc<br />

N<br />

iv<br />

+<br />

Ph<br />

Ph<br />

Ph<br />

Ph<br />

93% Ph Ph<br />

Ph<br />

iii<br />

ii<br />

NBn<br />

89%<br />

OH<br />

O<br />

O<br />

96%<br />

O O<br />

meso- 323b<br />

ds = 94%<br />

63b<br />

i: PhCH2MgCl, Et2O, −55 ° C, 3 h; ii: Et2AlCl, Et2O, rt, 30 m<strong>in</strong>, then PhCH2MgCl, −78 ° C, 3 h;<br />

iii: H2 (1 atm), Pd(OH) 2, AcOH/EtOH (90%), 15 h; iv: HCl/dioxanc (4.8 M), 0 ° C then rt, 20 h.<br />

Scheme 2.137

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