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16.12.4.2.2.1 Generation of N-Oxides

DOI: 10.1055/sos-SD-116-00063

von Angerer, S.Science of Synthesis Knowledge Updates, (20111447.

Oxidation of pyrimidines with peroxycarboxylic acids such as peracetic acid or 3-chloroperoxybenzoic acid results in the formation of N-oxides. In the absence of electron-releasing substituents yields are low. The reduced basicity of the second nitrogen after the first oxidation generally prevents the formation of dioxides. Unsymmetrically substituted pyrimidines can form 1- or 3-oxides, but generally the formation of one isomer is preferred. Occasionally, both possible oxides are isolated in comparable quantities.[‌1198‌‌1200‌] During the formation of the N-oxides oxidation-sensitive substituents such as nitroso or alkylsulfanyl groups are also oxidized.[‌794‌] Examples of the preparation of N-oxides 741 from pyrimidines 740 are given in Scheme 412. Favorable conditions for the preparation of the aminopyrimidine 1-oxides 741 (R1 = R3 = R4 = H; R2 = NH2) and 741 (R1 = NH2; R2 = R3 = R4 = H) comprise 3-chloroperoxybenzoic acid as oxidizing agent and 2 equivalents of hydrogen fluoride.[‌1201‌]

Meeeee 888 Meeeeeeeee 8-Meeeee ee Meeeeeeee ee Meeeeeeeeee[‌888‌,‌888‌,‌8888‌,‌8888‌‌8888‌]

Meeeeeeeeee 888

M8 M8 M8 M8 Meeeeeeeee Meeee (%) Mee
Me M M M MeMMM, 88°M, 8 e 88 [‌8888‌]
MM8 M M M MMMMM, MeMM, 88°M, 8 e 88 [‌8888‌]
Me Me M M MeMMM, Me8MM8, 88°M, 88 e 88e [‌8888‌]
Me Me MM Me 8-M8MM8M8MM8M, eeeeeee, 88–88°M, 8–88 e 88 [‌8888‌]
MM8 M M M MMMMM, MM, MMM, MeMM, 88°M, 88 eee 88 [‌8888‌]
M MM8 M M MMMMM, MM, MMM, MeMM, 88°M, 88 eee 88 [‌8888‌]
MM8 M M Me MMMMM, MeMM, 88°M, 8 e 88 [‌8888‌]
MM8 MM8 M Me MMMMM, MMMe8, ee, 88 e 88 [‌888‌]
MM8 M M MM8 M8M8, MMM, 8 ee 88°M, 88 e 88 [‌8888‌]
MM8 Me M MM8 MMMMM, MM, MMM, MeMM, 88°M, 88 eee 88 [‌8888‌]
eMe Me M Me M8M8, eeeeee eeeeeeeee, MMMe8, 8°M, 8 e 88 [‌8888‌,‌8888‌]
Me Me M Me M8M8, MeMM, 88°M, 8 e 88 [‌8888‌]
M MMe Me M MMMMM, MMMe8, ee, 88 e 88 [‌888‌]
M M MMe M MMMMM, MMMe8, 88°M, 8 e 88 [‌8888‌]

e Meeeeeee eeee 88% ee eee 8-eeeee.

Mee eeeeeeeee ee eeeeeeeeeee eeeeeee eeeeeeeeee eeeeeeeeeeee ee eeeee eeeeeeeeeeee eeee eeeeee eeeee eeeeeeeee ee eeee eeee eeeeeeee eeeeeeee eee eee eeeeeeeeee eeee ee eee eeeeeeeee, ee eeeeeeeeeee ee eee eeeeeeeeee ee eeeeeee eeeeeeeeeeeeeeee eeee eee eeeeeeeeeeeee M-eeeeee eeee eeeeee eeeeeeeee eee eeeeeeee eeeeeeee.[‌8888‌,‌8888‌] Meee eeeeeeee, eee eeee–eeeeeeee eeeeeeee eeeeeeee eeeeeee ee eeeeeeeeeee eeee eeeeeeeeeeeeeee eeeeeeeee eee eeee eeeeeeeeee ee eeeeeeeee eeeee eee eee eeeeeeeeeee ee eeeeeeeeeeee M-eeeeee. 8-Meeeeeeeeee eeeeeeeeeee 888 eee eeeeeeeee eeee eee eeeeeeeeeeeee M-eeeeee 888 ee eeee eeeee (Meeeee 888).[‌8888‌]

Meeeee 888 Meeeeeeeee M-Meeeee ee Meeeeeeee eeee Meee–Meeeeeee Meeeeeee Meeeeee ee eee Meeeeeee ee Meeeeeeeeeeeeee Meeeeeeee[‌8888‌]

Meeeeeeeeee 888

M8 Meeee (%) Mee
Me 88 [‌8888‌]
8-MeM8MM8M8 88 [‌8888‌]

Meeee eeeeeee eeeeeeeeee eeeeeeeeee 8,8-eeeeeeee eee ee eeeeeeee, ee eeeeeeeeeee ee eee eeeeeeee ee 8-eeeeee-8-eeeeeeeeeeeeeeee-8,8-eeeeeee eeee eeeeeeee eeeeeeee ee eeeeeeeeeeeeeee eeee, eeeeeeeee eee eeeeeeeeeeeee 8,8-eeeeeee ee 88% eeeee.[‌888‌] Meeeeeeee ee 8-eeeeeeeeeeeeeeeee-8,8,8-eeeeeeee (888) eeeee eeeeeee eeeeeeeeee eeeee 8,8,8-eeeeeeee-8-eeeeeeeeeeeeeee 8,8-eeeeeee (888) ee e eeeee eeeeeeeeeee eeeeeeeee (Meeeee 888).[‌8888‌]

Meeeee 888 8,8,8-Meeeeeee-8-eeeeeeeeeeeeeee 8,8-Meeeeeee ee Meeeeeeee ee 8-Meeeeeeeeeeeeeeee-8,8,8-eeeeeeee eeee Meeeeeee Meeeeeee ee Meeeeeeeeeeeeee Meee[‌8888‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeeeeeeeeeeee 8-Meeee (888, M8 = MM8; M8 = M8 = M8 = M); Meeeeee Meeeeeeee eee Meeeeeeee eeee 8-Meeeeeeeeeeeeeeeeee Meee:[‌8888‌]

MMMMMMM: Meeeeeee eeeeeeee eeeee eee eeeeeeee eeeeeeeeee eee eeeeeeeee eeeeeeeeeee ee eee eeeeeeeeeee eeeeee.

Me e eeeeeee eeee ee eeeeeeeee-8-eeeee (888, M8 = MM8; M8 = M8 = M8 = M; 888 ee, 8.8 eeee) ee MMM (88 eM) eee MeMM (8 eM) eee eeeee 88% ee MM (8.8 eM, 8.8 eeee) eee 88% MMMMM (8.88 e, 8.8 eeee). Mee eeeeeee eee eeeeeee eee 88 eee ee 88°M eee eeeeee eeeeee eeee eeee M8M (888 eM) eeeee eeeeeeee. Mee eeeeeeeeeeee eeeee eee eeeeeee ee eeeeeeeeee eee eee eeeeeeee eee eeeeeeeeeeee. Mee eeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MM8Me8/MeMM/MM8MM 8:8:8.8) ee eeeeee eee eeeeeee; eeeee: 88%; ee 888–888°M.

Meeeee 8-(8-Meeeeeeeeeeeee-8-ee)eeeeeeee (888, M8 = 8-MeM8MM8M8); Meeeeee Meeeeeeee:[‌8888‌]

M eeeeeee ee eeee–M8M8 eeeeeee (88 eeee) eee M8MM8 (88 eeee) ee MMMe8 (888 eM) eee eeeeeee eee 8 e eeeeee MMMM (88 eeee) eee eeeee eeeeeeee ee e eeeeeeeeeee eeeee 88°M. Mee eeeeeee eee eeeeeee ee eeeee ee, eeeeee 8-(eeeeeeeee-8-ee)eeeeeeee (888, M8 = 8-MeM8MM8M8; 8 eeee) eee eeeee, eee eee eeeeeee eee eeeeeee ee 88°M eeeeeeeee. Mee eeeeeee eee eeeeee eeee M8M (88 eM). Mee eeeeeee eeeee eee eeeee (MeMM8), eee eee eeeeeee eee eeeeeee. Mee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MMMe8/MeMM 88:8) ee eeee eee eeeeeee ee eeeee eeeee; eeeee: 8.888 e (88%); ee 888–888°M.

References


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