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

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596 NITRONATES<br />

Two component [4+2] [4+2] [4+2] dom<strong>in</strong>o cycloaddition<br />

MeO<br />

+<br />

Ph<br />

270 271<br />

Ph<br />

O2N<br />

207 : 271 = 3:1<br />

OMe<br />

NO 2<br />

15 kb,<br />

50 ° , 18 h<br />

Ph<br />

O 2N<br />

271<br />

OMe<br />

O<br />

N<br />

H Ph H<br />

O<br />

272 R<br />

273a<br />

1 = NO2; R2 = Ph;<br />

R1 = Ph; R2 = NO2;<br />

Ph<br />

O 2N<br />

Three component [4+2] [4+2] [4+2] dom<strong>in</strong>o cycloaddition<br />

MeO NO2<br />

+ 2,0 eq +<br />

MeO<br />

Ph<br />

270 271<br />

O<br />

R<br />

274a,b<br />

+ 2,0 eq N Ph +<br />

270 276<br />

O<br />

Ph<br />

271<br />

NO2<br />

15 kbar, r.t.<br />

16 h, 64%<br />

O H OMe<br />

O<br />

N O<br />

+ Ph N<br />

NO2 +<br />

O H<br />

277b<br />

H<br />

Ph Ph<br />

277a/277b ~ 0,65 / 0,35<br />

Scheme 3.175<br />

R 2<br />

R + 1<br />

Ph<br />

O2N<br />

271<br />

OMe<br />

O<br />

N<br />

H Ph H<br />

O<br />

NO 2<br />

273b<br />

272: 273a:273b = 0,2/ 0,6/ 0,2<br />

OMe<br />

O<br />

H<br />

Ph<br />

N<br />

O<br />

OMe<br />

O<br />

N<br />

H Ph H<br />

275a,b<br />

O<br />

Ph<br />

a-R = CO2Me, 4 diastereomeres<br />

b-R = Ph3 3diastereomeres<br />

O H OMe<br />

O<br />

N O<br />

Ph N<br />

+<br />

Ph<br />

O<br />

O<br />

N<br />

H<br />

H Ph H<br />

277a<br />

+<br />

OMe<br />

O<br />

N O<br />

Ph<br />

O Ph NO2<br />

278<br />

277/278 ~ 1 : 1<br />

NO 2<br />

Ph<br />

R

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