Attempted Hofmann elimination of an amine containing a hydroxy group on the b-carbon gives an oxacyclopropane product instead of an alkene. 

(a) Propose a sensible mechanism for this transformation. (b) Pseudoephedrine (see Problem 42) and ephedrine are closely related, naturally occurring compounds, as the similar names imply. In fact, they are stereoisomers. From the results of the following reactions, deduce the precise stereochemistries of ephedrine and pseudoephedrine. 

Problem 42

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1. Excess CH;I NH2 2. Ag.0, H,о Но 3. Д H,C-CH, → H2C-CH2 + (CH3)3N