Tin tetrachloride dihydrate → 5-Amino-2-[2-(4-amino-phenyl)-vinyl]-benzenesulfonic Acid, 2,2-Dimethylpropyl Ester

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Reaction Steps

5-Nitro-2-[2-(4-nitro-phenyl)-vinyl]-benzenesulfonic acid 2,2-dimethylpropyl ester (Example 56, 1.10 g, 2.62 mmol) was dissolved in 52 mL of ethyl acetate. Tin chloride dihydrate (2.95 g, 13.1 mmol) was added and a reflux condenser attached. The solution was heated to reflux and stirred overnight. After cooling to room temperature the solution was diluted with ethyl acetate (300 mL) and washed with saturated sodium bicarbonate. The whole mixture was filtered thru Celite and the aqueous layer discarded. The organic layer was then washed with brine and dried over MgSO4. After concentration on a rotovap the crude material was purified by a gradient flash column using 3 to 10% ethyl acetate in dichloromethane as the eluant to afford 0.33 g of the title compound as a oily red solid (35%): 1HNMR (CDCl3): δ7.63 (d, J=9 Hz, 1H), 7.58 (d, J=16 Hz, 1H), 7.33 (d, J=9 Hz, 2H), 7.31 (d, J=3 Hz, 1H), 6.89 (dd, J=9 Hz, 3 Hz, 1H), 6.86 (d, J=16 Hz, 1H), 6.68 (d, J=9 Hz, 2H), 3.89 (br s, 4H), 3.61 (s, 2H), 0.86 (s, 9H); MS (ES-POS): [M+H]+ 361; Analytical HPLC determined that this compound was 90% pure by C-18 reverse phase.

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