Sulfuric Acid → (3AS,6aR)-1,3-dibenzyltetrahydro-1H-furo(3,4-d)imidazole-2,4-dione

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Reaction Steps

A mixture of 4.0 g of the tetrahydroimidazol-2-one prepared in Example 11, 50 ml of dioxane and 30.0 g of 20 % sulfuric acid is stirred and refluxed for 2 hours. The mixture is concentrated to one third of the original volume in vacuo and diluted with 100 ml of water. The precipitate is collected by filtration to give 1.26 g (96.5 %) of optically active (+)-cis-1,3-dibenzyl-hexahydrofuro[3,4-d]imidazole-2,4-dione. M.P. 106 to 109° C. [α]D20 + 16.0° (C = 2 in CHCl3). The infrared spectrum of the sample is identical with that of the authentic sample.

Provenance & Evidence