The stereoelectronically controlled reaction of 2-methoxy-1,3-dioxane ( ) with Grignard reagents does not follow the course suggested by the behavior of anancomeric models for the conformational isomers of . Treatment of with RMgX leads to the predominant formation of acid labile 3-(1′-methoxyalkoxy )-1-propanols, derived from endocyclic cleavage of the ring CO bond, and only minor amounts of the expected 2-R-1,3-dioxanes. ... Acetals having the structure of would be named ...