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

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692 NITRONATES<br />

Table 3.34 The coupl<strong>in</strong>g of nitroso acetals 475 with nucleophiles (20 ◦ C, CH2Cl2)<br />

(528)<br />

Nu-Y Yield<br />

Entry (Y–H or SiMe3) R 1 R 2 R 3 R 4 R 5 Product %<br />

1 Morphol<strong>in</strong>e H An H OMe Me (480a + 481a) 70<br />

2 Morphol<strong>in</strong>e H An H OEt H (481b) 71<br />

3 Morphol<strong>in</strong>e H Ph H OMe Me (480c + 481c) 60<br />

4 Morphol<strong>in</strong>e H Ph H Me Me (479a) 69<br />

5 n-BuNH2 H Ph H Me Me (479b) 76<br />

6 n-BuNH2 H An H OMe Me (482a) 91<br />

7 Me3SiCN a H An H OMe Me (476a) 95<br />

8 n-BuNH2 H An H OEt H (482b) 92<br />

9 Me3SiCN a H Ph H Me Me (476b) 98<br />

10 Me3SiN3 a H An H OMe Me (477a) 84<br />

11 Me3SiN3 a H Ph H Me Me (476c) 92<br />

12 Me3SiCl b H An H OMe Me (476d) 87<br />

13 Bu t Me2SiCl b H An H OMe Me (477b) 56<br />

14 Me3Si-N-pyrazol a H An H OMe Me (477c) 74<br />

15 Me3Si-N-pyrazol a H An H OEt H (478a) 73<br />

16 Me3Si-N-pyrazol a H Pr H Me Me (476e) 92<br />

17 Me3Si-N-imidazole a H An H OMe Me (478b) 87<br />

18 Me3Si-N-imidazole a H An H OEt H (478c) 85<br />

19 Me3Si-N-imidazole a H An -(CH2)4- H (476f) 67<br />

20 Me3SiCl b H Ph H OMe Me (476g) 92<br />

21 Me3Si-N-imidazole a H Ph H Me Me (476h) 74<br />

22 Me3Si-N-imidazole a Me An H OMe Me (478d) 32<br />

23 1-Me3Si-triazole-1,2,3 a H An H OMe Me (477d) 42<br />

24 1-Me3Si-triazole-1,2,3 H An H OMe Me (478e) 47<br />

25 1-Me3Si-triazole-1,2,3 a H Ph H OMe Me (477e) 41<br />

26 1-Me3Si-triazole-1,2,3 a H Ph H Me Me (476i) 41<br />

27 1-Me3Si-triazole-1,2,3 a H An H OMe Me (477f) 35<br />

28 1-Me3Si-triazole-1,2,3 H An H OMe Me (478f) 38<br />

29 1-Me3Si-triazole-1,2,3 H Ph H OMe Me (477g) 39<br />

30 1-Me3Si-triazole-1,2,3 H Ph H Me Me (476j) 45<br />

a 5% Et3N.<br />

b N-methyl-imidazole.<br />

One approach is based on the generation of radicals R ′ by UV irradiation of<br />

alkyl halides R ′ I together with hexaalkyldistannanes (Scheme 3.257).<br />

The result<strong>in</strong>g radicals R ′ efÞciently alkylate BENAs (495) attheβ-C atom to<br />

give silyl derivatives of oximes (496) <strong>in</strong> good yields. The latter readily undergo<br />

deoximation <strong>in</strong> the presence of 1 M hydrochloric acid to give the correspond<strong>in</strong>g<br />

carbonyl compounds (494). Thus, a convenient procedure was developed for the<br />

synthesis of carbonyl compounds (494) from secondary AN (493) through the<br />

<strong>in</strong>termediate term<strong>in</strong>al BENA (495) (527).

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