p-Toluenesulfonic acid monohydrate → dihydro-4-(3,5-di tert-butyl-4-hydroxybenzylidene)-2-isopropyl-2H-1,2-oxazin-3(4H)-one

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Reaction Steps

The dihydro-4-[(3,5-di-tert-butyl-4-hydroxyphenyl)hydroxymethyl]-2-isopropyl-2H-1,2-oxazin-3(4H)-one of Step B was refluxed in 40 ml of benzene with a catalytic amount of p-toluenesulfonic acid monohydrate for 6 hours and concentrated in vacuo. The concentrate was triturated in ether and filtered to yield 0.9 g (2.5 mmol) of dihydro-4-(3,5-di tert-butyl-4-hydroxybenzylidene)-2-isopropyl-2H-1,2-oxazin-3(4H)-one, mp 181°-183° C.

Provenance & Evidence