SE323084

Chromane compounds of formula where R1 is a hydrogen or halogen atom and R2 is a hydrogen atom or an acyl group, are obtained by cyclizing 2 - [(3R, 7R, 11R) - 3,7, 11,15-tetramethyl - 3 - hydroxy - hexadacyl] - trimethyl-p-benzoquinone in the presence of an acidic cyclization agent. The reaction may be carried out at 0 DEG to 40 DEG C. The acidic cyclization agent may be a mineral acid, e.g. sulphuric acid or phosphoric acid (preferably used with a solvent, e.g. methanol, ethanol or iso-propanol) or an alkanoic acid halide, e.g. acetyl chloride or propionyl chloride (used without a solvent). When a mineral acid is used [2R, 41R, 81R]-alpha-tocopherol is obtained directly; when an alkanoyl halide is used R1 is a halogen atom and R2 is an acyl group. Examples are given.