2,6-Diethoxy-l ,4-oxathiane

Diels-Alder reaction, 50, 37 of 1,4-diacetoxy-l,3-buta-diene, 50, 27 using 3-sulfone, 50, 47 2,6-Diethoxy-l,4-oxathiane, 52, 135... 

This procedure represents the first reported synthesis of cis- and further reaction product, 4//-l,4-thiazine 1,1-dioxide. A derivative of the latter, 3,5-diphenyl-4//-l, 4-thiazine 1,1-dioxide,... 

The filtrate is cooled to 0° in a refrigerator overnight. The resulting precipitate is filtered, giving cis- and trans-2,6-diethoxy-l,4-oxathiane 4,4-dioxide as a white solid (42-46 g., 74-81%), m.p. 83-117° (Note 7). 

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