Bromide ion → 2-Phenyl-2-propanol

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Reaction Steps

When n is the bridging group --C(CH3)2 --, an appropriately substituted or unsubstituted phenyl methyl ketone, for example, methyl (3-chlorophenyl) ketone, is prepared by the reaction of methylmagnesium bromide and an appropriate benzonitrile in tetrahydrofuran. The ketone is in turn treated with methylmagnesiun bromide in tetrahydrofuran, yielding the corresponding 2-phenylpropan-2-ol, which is then converted to the 2-bromo-2-phenylpropane by the treatment of the alcohol with lithium bromide and trimethylsilyl chloride in acetonitrile. The Grignard reagent of the 2-bromo-2-phenylpropane is then prepared and reacted with 1,4-cyclohexanedione mono-ethylene ketal in tetrahydrofuran, yielding the corresponding 1-(2-phenylpropan-2-yl)-1-cyclohexen-4-one. The so-prepared cyclohexenone is reduced with hydrogen gas in the presence of 10% palladium on charcoal, yielding the 4-(2-phenylpropan-2-yl)cyclohexanone, which is in turn reacted with cyanoguanidine, as previously described, yielding the targeted 2,4-diamino-6-(2-phenylpropan-2-yl)-5,6,7,8-tetrahydroquinazoline. Example 7 provides a detailed description of how this reaction is conducted.

Provenance & Evidence