Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content.
12.1.1.2.1.1.1.1 Variation 1: From Malonaldehyde Acetals and Hydrazines

DOI: 10.1055/sos-SD-012-00002

Stanovnik, B.; Svete, J.Science of Synthesis, (20021223.

The O,O-acetals of 1,3-dicarbonyl compounds are employed for the synthesis of many pyrazole derivatives. 1,1,3,3-Tetraalkoxypropanes are used for the preparation of 3,4,5-trisubstituted pyrazoles, while 1,1,3,3-tetraalkoxybutanes give 3-methyl-substituted pyrazoles. The reactions are carried out in water, a mixture of water and ethanol, or in ethanol at a temperature of 0100°C. To facilitate the cleavage of the acetals and cyclization to pyrazole derivatives, the reaction is either carried out in the presence of mineral acids or the hydrazine dihydrochlorides or dihydrosulfates are used.[‌75‌‌77‌] By heating of equimolar amounts of 1,1,3,3-tetraethoxypropane and arylhydrazines in 95% ethanol the corresponding 1-arylpyrazoles 5 are obtained in good yields (Scheme 7).[‌75‌,‌76‌]

Meeeee 8 8-Meeeeeeeeeeee eeee 8,8,8,8-Meeeeeeeeeeeeeeeeee eee Meeeeeeeee[‌88‌,‌88‌]

Meeeeeeeeee 8

M8 Meeeeeeeee Meeee (%) Mee
M M8MMM88MMe, M8M, MeMM, eeee 8888 [‌88‌]
Me MeMMMM8MMe, MeMM, eeeeee 88 [‌88‌]
8-M8MM8M8 8-M8MM8M8MMMM8MMe, MeMM, eeeeee 88 [‌88‌]
8-M8MM8M8 8-M8MM8M8MMMM8MMe, MeMM, eeeeee 88 [‌88‌]
8-M8MM8M8 8-M8MM8M8MMMM8MMe, MeMM, eeeeee 88 [‌88‌]
8,8-(M8M)8M8M8 8,8-(M8M)8M8M8MMMM8MMe, MeMM, eeeeee 88 [‌88‌]

Meeeeeeeeeee Meeeeeeee

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

M eeeeeee ee 8,8,8,8-eeeeeeeeeeeeeeeeee (888e, 8eee), M8MMM88MMe (888e, 8eee), M8M (888eM), eee MeMM (888eM) eee eeeeee ee eeeee eeee eee 8e, eeeeee, eee MeMM eeeeeee ee eeeeeeeeeee ee eeeee. Mee eeeee eeeeeeee eeeee eee eeeee ee ee M8M (888eM) eee eee eeee eeeeeeeeeee ee eeeeeeee ee MeMMM8 (888e). Mee eeeeeeeeeee eeeeeeee eee eeeeeee ee eeeeeeeeee eee eeeeee eeee Me8M (8×888eM), eeeee eee eeee eeee ee eeeeeee eee eeeeeeee. Mee eeeee Me8M eeee eee eeeeeeeeee ee eeeee eee eee eeeeeee eeeeeeeee ee eeeeeeeeee eeeeeeee ee eeee eeee eeee eeeeeee; eeeee: 8888%; ee 8888°M/88Meee; ee 88°M.

8-Meeeee-8M-eeeeeeee (8, M8=Me); Meeeeee Meeeeeeee:[‌88‌]

M eeeeeee ee 8,8,8,8-eeeeeeeeeeeeeeeeee (88e, 8.8eee), MeMMMM8MMe (88.8e, 8.8eee), eee MeMM (88%, 888eM) eee eeeeeeee eee 88eee, eeeeee, eee MeMM eeeeeee ee eeeeeeeeeee ee eeeee. Mee eeeee eeeeeeee eeeee eee eeeee ee ee M8M (888eM) eee eee eeee eeeeeeeeeee ee eeeeeeee ee MeMMM8 (88e). Mee eeeeeeeeeee eeeeeeee eee eeeeeee ee eeeeeeeeee eee eeeeee eeee Me8M (8×888eM), eeeee eee eeee eeee ee eeeeeee eee eeeeeeee. Mee eeeee Me8M eeee eee eeeeeeeeee ee eeeee eee eee eeeeeee eeeeeeeee eeeee eeeeeee eeeeeeee; eeeee: 88%; ee 88°M/8.88Meee.

References


Cookie-Einstellungen