Acid‐Induced and Reductive Transformations of Enantiopure 3,6‐Dihydro‐2 H ‐1,2‐oxazines – Synthesis of Dideoxyamino Carbohydrate Derivatives

Acid‐catalyzed transformations of carbohydrate‐derived 3,6‐dihydro‐2 H ‐1,2‐oxazines such as 1 , 5 and 13 provided a set of enantiopure furano‐1,2‐oxazines or pyrano‐1,2‐oxazines. The reaction conditions determined the degree of solvolysis of the compounds. An X‐ray analysis of product 6 revealed an interesting network of hydrogen bonds. Reductive cleavage of the N–O bond of the 1,2‐oxazines either by hydrogen/palladium or by samarium diiodide furnished enantiopure aminofuran and ‐pyran derivatives, e.g. 9 and 11 or compound 16 , which can be regarded as protected 4‐amino‐1,4‐dideoxyhex‐3‐ulose or 4‐amino‐1,4‐dideoxyoct‐3‐ulose derivatives. We thus have established a short and stereocontrolled route to amino carbohydrate derivatives with 1,2‐oxazines as crucial relay compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)