Reaction of 2-methoxy-1,3-dioxane with grignard reagents: reagent-substrate complexation and stereoelectronic control.

The stereoelectronically controlled reaction of 2-methoxy-1,3-dioxane ($\text{1}$) with Grignard reagents does not follow the course suggested by the behavior of anancomeric models for the conformational isomers of $\text{1}$. Treatment of $\text{1}$ with RMgX leads to the predominant formation of acid labile 3-(1′-methoxyalkoxy)-1-propanols, derived from endocyclic cleavage of the ring CO bond, and only minor amounts of the expected 2-R-1,3-dioxanes.