5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-2-carbaldehyde synthesis

Yield:623564-46-5 91%

Reaction Conditions:

with manganese(IV) oxide in chloroform; for 1 h;Heating / reflux;

Steps:

8.3

Step 3: 5. 6-Dihvdro-4H-pyrrolor1, 2-blpvrazole-2-carbaldehyde; Mn02 (activated) (24.4 g) was added to the CHCI3 (350 mL) solution of (5,6- dihydro-4H-pyrrolo [1, 2-b] pyrazol-2-yl) methanol (4.87 g) and refluxed for 1 h under a nitrogen atmosphere. The reaction mixture was filtered through a pad of Celite. The filtrate was reduced under reduced pressure. The residue was applied to silica gel column chromatography, then the column was eluted with n-hexane-AcOEt (1/1 -1/2). The title compound was obtained as yellow oil (4.35 g, 91%). 'H NMR (CDCI3) 8 2.63-2. 71 (m, 2H), 2.95 (t, 2H, J = 7.4 Hz), 4.22 (t, 2H, J = 7.4 Hz), 6.52 (s, 1H), 9.89 (s, 1 H).

References:

WO2003/93279,2003,A1 Location in patent:Page/Page column 67-68