Pyrrole-2-carboxaldehyde → tert-Butyl 2-formyl-1H-pyrrole-1-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A mixture of pyrrole-2-carboxaldehyde (9.5 g, 0.1 mol), (BOC)2O (24.0 g, 0.11 mol) and DMAP (0.25 g) in THF (150 ml) was stirred at room temperature for 16 h. The solvent was removed under vacuum and the residue dissolved in CH2Cl2 (200 ml) and washed with 10% citric add, water and brine. The organic layer was dried (Na2SO4) and evaporated to give the desired product (20.9 g, 95%); δ (360 MHz, CDCl3) 1.65 (9H, s, 3 of CH3), 6.28-6.30 (1H, m, Ar--H), 7.18-7.19 (1H, m, Ar--H), 7.43-7.45 (1H, m, Ar--H). 2. trans-Methyl-2-N-tert-butyloxycarbonylpyrrol-2-yl)acrylate Prepared from the preceding aldehyde and methyl diethylphosphonoacetate as described for Intermediate 4 (step 3). The product (98%) was obtained as a pale yellow oil; δ (360 MHz, CDCl3) 1.63 (9H, s, 3 of CH3), 3.78 (3H, s, CH3), 6.21 (1H, d, J=16.0 Hz, vinyl CH), 6.21-6.22 (1H, m, Ar--H), 6.69-6.71 (1H, m, Ar--H), 7.38-7.39 (1H, m, Ar--H), 8.30 (1H, d, J=16.0 Hz, vinyl CH).

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