Navigation

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
33.4.1.1.1.1 Variation 1: Nitration of Vinylsilanes or Vinylstannanes

DOI: 10.1055/sos-SD-033-00448

Ono, N.Science of Synthesis, (200733342.

In general, cyclic nitroalkenes are more difficult to prepare than acyclic ones. Vinylsilanes and vinylstannanes are readily prepared from various sources, and nitration of these substrates with cyclic substituents provides an efficient method for the preparation of cyclic nitroalkenes. Cyclic ketones are converted into vinylsilanes or vinylstannanes via arylhydrazone intermediates. Reaction of acetyl nitrate with six- or seven-membered ring vinylsilanes gives the corresponding nitrocycloalkenes, for example 1-nitrocyclohexene (7) (Scheme 5) and 1-nitrocycloheptene. On the other hand, the reaction with medium and large ring vinylsilanes such as 1-(trimethylsilyl)octene does not give nitrocycloalkenes, but gives novel 1,1-dinitro 2-nitrates.[‌53‌] Cyclic nitroalkenes can also be prepared from cyclic ketones via nitration of vinylstannanes with tetranitromethane in dimethylsulfoxide, where dimethylsulfoxide is a critical choice of solvent for replacing tin by nitro at the unsaturated carbon.[‌54‌] The vinylstannanes can be prepared in good yield from the ketones, via arylhydrazone intermediates.[‌55‌] Thus, cycloheptenone was converted into 1-nitrocycloheptene (11) by this procedure (Scheme 5). Regioselective stannylation of benzofurans can also be achieved by the direct lithiation of the furan ring with tert-butyllithium and subsequent treatment with chlorotrimethylstannane, and nitration with tetranitromethane to give, for example, 2-nitrobenzo[b]furan 12 in 72% yield (Scheme 5).[‌56‌]

Meeeee 8 Meeeeeeee ee Meeeeeeeeeee ee Meeeeeeeeeeeee[‌88‌,‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeeee

8-Meeeeeeeeeeeeeee (8); Meeeeee Meeeeeeee:[‌88‌]

8-(Meeeeeeeeeeeee)eeeeeeeeeee (8.8eeee) ee MM8Me8 (8eM) ee 88°M eee eeeeeee eeeeeeee eeee MeMMM8 (8eeee). Meeee eeeeeeee eee eeeeeee eee 88eee, M8M eee eeeee eee eee eeeeeee eee eeeeeeeee (MM8Me8). Mee eeeeeeee eeee eeeeee (M8M) eee eeeee (Me8MM8). Mee eeeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:88) ee eeee eee eeeeeee; eeeee: 88%.

8-Meeeeeeeeeeeeeeee (88):[‌88‌]

Me e eeee ee 8-(eeeeeeeeeeeeeeee)eeeeeeeeeeee (888ee, 8.8eeee) ee eeeee MMMM (8.8eM) eee eeeee M(MM8)8 (888ee, 8.8eeee) eeee 8eee. Mee eeeeeeeee eeee eee eeeeeee ee 88°M eeeee eeeee eee 8.8e. Mee eeeeeee eee eeeeee eeee M8M (888eM) eee eeeeeeeee eeee eeeeeee (8×88eM). Mee eeeeeee eeeee eee eeeeee eeee M8M (8×8eM). Meeeeeeeee ee eee eeeeeee eeeeeee e eeeee eeeeee [eeeeee eee (88e), eeeeeee/eeeeee 8:88] eeeeeeee eeee eeeeeee; eeeee: 888ee (88%).

References


Cookie-Einstellungen