7-Methoxy-4-methyl-4H-benzo[1,4]oxazin-3-one → 4-methyl-7-methoxy-3,4-dihydro-2H-[1,4]benzoxazine

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Reaction Steps

Still following the procedure of Example 1, 21 g of 4-methyl-7-methoxy-3,4-dihydro-2H-[1,4]benzoxazin-3-one were reduced with 1M BH3 in THF solution. The reaction was carried out and the product isolated by the procedure of Example 1 to yield 4-methyl-7-methoxy-3,4-dihydro-2H-[1,4]benzoxazine; B.P.=105° C. at 0.025 torr; yield=16 g. Following the procedure of Example 1, 16 g of the above 4-methyl-7-methoxy-2H-[1,4]benzoxazine was subjected to a Birch reduction with lithium metal in anhydrous ammonia as follows: the oxazine was dissolved in 75 ml of THF and the solution added to a solution of 4.42 g of lithium metal dissolved in 300 ml of anhydrous ammonia. 100 ml of anhydrous ethanol were added during the course of the reaction. The product, 4-methyl-7-methoxy-3,4,5,8-tetrahydro-2H-[1,4]benzoaxazine, weighed 15.2 g.

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