Benzyl chloroformate → Benzyl (2,2-dimethoxyethyl)[2-(4-hydroxy-2-oxo-2,3-dihydro-1,3-benzothiazol-7-yl)ethyl]carbamate

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Reaction Steps

7-(2-Aminoethyl)-4-hydroxy-1,3-benzothiazol-2(3H)-one hydrobromide (20 g) was dissolved in a mixture of THF (300 ml) and water (150 ml). Sodium hydrogen carbonate (5.77 g) was added and the mixture stirred for 15 min. Acetic acid (7.86 ml) was added, followed by dimethoxyacetaldehyde (14.9 g, 12.91 ml) and the mixture stirred for a further 30 min. Sodium cyanoborohydride (8.64 g) was added portion-wise over 10 min and the solution stirred for a further 20 h. Ethyl acetate (500 ml) and a solution of sodium hydrogen carbonate (17.33 g) in water (250 ml) were added, the mixture was stirred vigorously, benzyl chloroformate (8.78 g, 7.35 ml) was added, and the mixture stirred for 2 h. The organic layer was separated, washed with water, 0.1M aq. HCl, water and brine, dried (anhydrous Na2SO4), filtered and evaporated. The resulting material was purified by flash chromatography on silica using 10% methanol in dichloromethane as eluent to give the sub-title compound as a light brown gum (23.1 g).

Provenance & Evidence