2-Methyl-3-butyn-2-ol → 4-(1,1-Dimethyl-2-propynyloxy)bromobenzene

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Reaction Steps

The 6-bromo-2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran used as the starting material was prepared as follows: (A) 69.2 g of p-bromophenol and 33.6 g of 2-methylbut-3-yn-2-ol were dissolved in 600 ml of dichloromethane and 75 ml of diethyl azodicarboxylate were added. 126 g of triphenylphosphine were added portionwise and the mixture was stirred overnight. The mixture was washed with dilute hydrochloric acid and 2M sodium hydroxide solution, dried over sodium sulphate and evaporated. The residue was chromatographed on silica gel using ethyl acetate/petroleum ether (1:10) for the elution. There was obtained an oil which was distilled to give 14.4 g of 4-(1,1-dimethyl-2-propynyloxy)bromobenzene of boiling point 96°-106° C./1 mmHg. (B) In an analogous manner to that described in Example 6(A), from 4-(1,1-dimethyl-2-propynyloxy)bromobenzene and 2-iodopyridine there was obtained 6-bromo-2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran.

Provenance & Evidence