Hydrogen Bromide → Ethyl 1-(7-chloroquinazolin-4-yl)-5-hydroxy-2-methylindol-3-ylacetate

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A solution of ethyl 5-benzyloxy-1-(7-chloroquinazolin-4-yl)-2-methylindol-3-ylacetate (1.5g) in glacial acetic acid (5ml.) was treated with a 50% w/v solution of hydrogen bromide in glacial acetic acid (5ml.). The resulting dark red solution was stirred at room temperature for 10 minutes and then neutralised by the addition to a mixture of saturated sodium acetate solution (50ml.) and water (150ml.). The mixture was extracted with ethyl acetate (3 × 50ml.) and the extracts washed successively with water (2 × 40ml.), saturated sodium hydrogen carbonate solution (2 × 40ml.), water (40ml.) and then saturated sodium chloride solution (40ml.). After drying (MgSO4), the extracts gave on evaporation in vacuo a yellow-brown oil. Purification by chromatography on silica gel (200g.) in a mixture of 50% v/v ether and 50% v/v petroleum ether (b.p 40°-60° C.), gave ethyl 1-(7-chloroquinazolin-4-yl)-5-hydroxy-2-methylindol-3-ylacetate as a pale yellow glass [NMR: 2-CH3 at 7.7 τ; pure by TLC (systems A, C and D)].

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