0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via Method 3: Nitrosation by Nitrosonium Tetrafluoroborate

DOI: 10.1055/sos-SD-031-01513

Rück-Braun, K.; Priewisch, B.Science of Synthesis, (2007311329.

Since deprotonation of the Wheland intermediate [Ar1+(H)NO] is the rate-determining step in the nitrosation of an arene (Ar1H) (see Section, the usual acid-catalyzed generation of nitrosonium cations is counterproductive. The use of commercially available nitrosonium tetrafluoroborate in acetonitrile offers the possibility of aromatic nitrosation in nonaqueous solution,[‌40‌] in which the reactions are conducted under argon at room temperature or below. Anisole (24, R1=R2=R4=R5=H; R3=OMe) and related methoxylated benzenes containing one or two methyl groups, but unsubstituted para to the ether group, are nitrosated in high yields to give the corresponding nitrosoamines 25 (Scheme 15). This occurs without hydrolysis of the ether linkage; a problem commonly observed during nitrosation of similar substrates under aqueous conditions. 15N-Labeled 1-methoxy-4-nitrosobenzene can be prepared by the use of 15N-nitrosonium tetrafluoroborate.[‌41‌] In contrast, the para-substituted compound 4-methoxytoluene (24, R1=OMe; R2=R3=R5=H; R4=Me) is considerably less reactive under the standard conditions, yielding only traces of a nitroso compound. Similarly, brominated anisoles react much less well than anisole and longer reaction times than usual are required in order to obtain the corresponding nitroso compounds; even so, the yields are mediocre.

Meeeee 88 Meeeeeeeeee eeee Meeeeeeeeee Meeeeeeeeeeeeeeee[‌88‌]

Meeeeeeeeee 88

M8 M8 M8 M8 M8 Meeeeeeeee Meeeeeeeee (%) Meeeee (%) ee (°M) Mee
M M MMe M M 88°M, 8.8e 888 88 8888 [‌88‌]
M Me MMe M M 8°M, 8.8e 888 88 8888 [‌88‌]
Me M MMe M M 8°M, 8.8e 888 88 8888 [‌88‌]
Me M MMe M Me 8°M, 8.8e 888 88 888888 [‌88‌]
Me M Me M Me ee, 8e 88 88 888888 [‌88‌]
Me M Me M M 88°M, 88e 88 88 88 [‌88‌]
M Me MMe M M 88°M, 88e 88 88 8888 [‌88‌]
Me M MMe M M 88°M, 88e 88 88 8888 [‌88‌]
MMe M M Me M 88°M, 8.8e 88 ee. 8 e [‌88‌]

e Meeee ee eee eeeeeeeeee.

e Mee eeeeeeee.

Meeeeee eeeeeeeeeeeeeeeeee, eeeeeeeeee ee eeeee eee eeeeee eeeeee eeeee eee eeee ee eee eeeeeeee ee ee eeeeeeeeeee eee eeee ee eeeeeeeeee eeeee eee eeeeeeeeee eeeeeeeee eeeee, eee ee eeeeeeeeee ee eeeeeeeeeeee eeeeeeee eeeee eeeeeeeee eee eeeeee eee eeee eeeeee eeeeeeee eeeee eee eeeeeeee ee eeeeee eeeeeeeeee eeeeeeeeeee. Me eee eeee ee e-eeeeee, eee eeeeeee, e eeeeeeeeeee ee 88°M eee e eeeeeeee eeee ee 88 eeeee eee eeeeeeeee ee eeeeee eee eeeeeee eeeeeeee 88 (M8=M8=Me; M8=M8=M8=M) (Meeeee 88). 8,8,8,8-Meeeeeeeeeeeeeeeee (88, M8=M) eee 8,8,8,8,8-eeeeeeeeeeeeeeeeee (88, M8=Me) eee eeeee eeeeeeeeee; eeee, eeee eeee eee eeeeeee eeee eeeeeeeeeee eeeeeeeeeeeeeeeee ee eeeeeeeeeeee ee eeee eeeeeeeeeee eee eeeeeee 8.8 eee 8 eeeee, eeee eeeeee eeee eee eeeeee ee eee eeeeeeeeeeeee eeeee eeeeeeeee 88, eeeeeeee eeee eee eeeeeeeee eeeeeeeeeeeeeeee 88 eeee eeeee eeeeeee eeeeeeeee eeeeeeeeeeee (Meeeee 88).[‌88‌,‌88‌]

Meeeee 88 Meeeeeeee ee Meeeeeeeeeeeeeeeee ee Meeeeeeeeee Meeeeeeeeeeeeeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeeee-8-eeeeeeeeeeeeee (88, M8=M8=M8=M8=M; M8=MMe); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeeee eeeeeee eee ee eeeeee eeeeeee eee eeeeeeeeeee eeeeeeeee. Meeeeeee eeeeeeeeee ee eeeeeeeee, eeeeeeeeee eeee eee eeeeee ee eeeeee ee eee eee ee eee eeeeeeeee.

M eee eee eee eeee ee eeeeee e Meeeeee eeee eeee MMMM8 (888ee, 8.8eeee) (MMMMMMM: eeeee). Mee eeee eee eeeeeeee eeee e eeeeeeee eeeeeeee eee eee eeeeee eeee e Meeeee eeeeeeee. MeMM (88eM) eee eeeeeeee eeeee e eeeeee ee eeeee eee eee eeeeeee eee eeeeeee, eeeee eee MMMM8 eee eeeeeeeeee eeeeeeeee. MeMMe (888μM, 8.88eeee) eee eeeee eee eeeeeee eeeee e eeee ee eeeee, eee eeee eee eeeeeeee, eee eee eeeeeeee eeee eeeeeee ee 88°M ee eee eeee eee 88eee. Mee eeee eeeee eeeeeee eee eeee eeeeee eeee e eeeeeeeeee eeeeeee eeeeeee ee MM8Me8 (88eM) eee M8M (88eM). Mee eeeeee eeee eeeeeeeee, eee eee eeeeeee eeeee eee eeeeee eeee M8M (8×88eM) eeeee eee eeeeeee eeeeeeee eeeeeeee eeeee. Mee eeeeeee eeeee eee eeeee (MeMM8) eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee ee eeeee e eeeeeee, eeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee/MM8Me8 8:8) eee eeeeeeeeeeeeeeeee (eeeeee) ee eeee eeee eeee eeeeeeee; eeeee: 888ee (88%); ee 8888°M.