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

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R 2<br />

SILYLATION OF NITRO COMPOUNDS AS A PROCESS 679<br />

Me3SiCN + Et3N CN − + [Me 3SiNEt 3] + ; Me 3SiCN Me3SiN + C −<br />

R 1<br />

H<br />

Me<br />

H<br />

R 1<br />

MeO2C(CH2)2<br />

Ph<br />

EtO 2C<br />

MeO2C<br />

N(OSiMe3)2<br />

R 2<br />

H<br />

H<br />

Me<br />

H<br />

H<br />

H<br />

Me<br />

CN −<br />

Me 3SiCN + OSiMe 3 −<br />

CN −<br />

Yield 451 %<br />

49<br />

79<br />

70<br />

61<br />

72<br />

42<br />

54<br />

H2N<br />

R 2<br />

A<br />

R 1<br />

N<br />

R 2 R 1<br />

O N<br />

451<br />

Scheme 3.242<br />

R 2 R 1<br />

O<br />

Me3SiCN NC N OSiMe3<br />

452<br />

R 2 R 1<br />

NC<br />

MeOH/Et3N<br />

N OH<br />

is presented below. It cannot be ruled out that trimethylsilyl isocyanide exist<strong>in</strong>g<br />

<strong>in</strong> equilibrium with trimethylsilyl cyanide is the true molecule <strong>in</strong>volved <strong>in</strong> the<br />

reaction (520).<br />

This process affords silyl derivatives of α-cyano oximes (452) as the primary<br />

products, detected by spectroscopic methods <strong>and</strong>, <strong>in</strong> some cases, can be isolated.<br />

Their desilylation gives am<strong>in</strong>ooxazoles (451). (The synthesis of am<strong>in</strong>oisoxazoles<br />

by the reactions of the cyanide anion with nitrosoalkenes was also documented<br />

(503).) The reaction shown <strong>in</strong> Scheme 3.242 has a general character <strong>and</strong> can be<br />

performed with both term<strong>in</strong>al <strong>and</strong> <strong>in</strong>ternal BENAs, although special procedures<br />

are required for some functionalized BENAs.<br />

3.5.4.2.2.2. reactions of BENAs with N -nucleophiles N -Centered nucleophiles,<br />

whose reactions with BENA have been studied (291), can be <strong>in</strong>tegrated<br />

<strong>in</strong>to two large groups: nitrogen bases (various am<strong>in</strong>o derivatives) <strong>and</strong> amphoteric<br />

compounds, which can exhibit both basic <strong>and</strong> acidic properties (polyazoles,<br />

N-nitroam<strong>in</strong>es <strong>and</strong> HN3 derivatives). The behavior of these two groups <strong>and</strong> the<br />

conditions of their N,C-coupl<strong>in</strong>g reactions with BENA considerably <strong>and</strong> different<br />

therefore are considered separately.<br />

N,C-Coupl<strong>in</strong>g Reactions of BENA with Am<strong>in</strong>es. As can be seen from Scheme<br />

3.243, the successful N,C-coupl<strong>in</strong>g of BENAs (434) with am<strong>in</strong>es allows one to

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