Saturated Six-Membered Rings with Two Heteroatoms

A comparison of 190 with 1,3-dioxane 177 shows that the anomeric interactions in 177 are much stronger than in 190. Moreover, the balance of the computed hyper-conjugative interactions successfully accounts for the relative C—Ha and C—Hgq 

The overall reaction is exothermic by -18.8 kcal/mol and proceeds via pre-complexation of the CO2. For further computational studies on dithianes, see Refs. [97BCJ2571, 99T5027]. 

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