Ethanolamine, from oxirane

Dioxanes are produced in excellent yields from oxiranes and dilute sulfuric acid. 1,4-Dioxanes are also conveniently obtained by acid-catalyzed condensation of oxiranes with glycols, while the reaction of oxirane with ethanolamine gives morpholine 482. Base-catalyzed reaction of oxiranes with -amino acids and esters gives tetrahy-dro-l,4-oxazin-2-ones, e.g., propene oxide + RNHCH2C02H 483. 1,4-Dithianes have been prepared by the dimerization of thiiranes either in the vapor phase or in the presence of acid catalysts. 

Disubstituted tetrahydro-l,4-oxazines are also obtained from the reaction of the ethanolamines (282) and oxiranes in the presence of 70% sulfuric acid. The protective N-benzyl substituent can be easily removed by hydrogenolysis over palladium on carbon (Scheme 125) (80T409). 2-Oxo derivatives are available if ethanolamines are replaced by a-amino acids, or if ethanolamines are reacted with a-bromoacetates (Scheme 126) (79CR(C)(288)229). 

Like piperidine, morpholine is used in pharmaceuticals as a secondary amine component. One of the drugs derived from morphoHne as a heterocycle is viloxazine (5), which can be obtained from the oxirane 4 by reaction with ethanolamine hydrogensulfate. Structurally related to 5 is reboxetine (6, in the form of the (S,S)-(- -)-stereoisomer). Both 5 and 6 are eflective as antidepressants. 

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See also in sourсe #XX -- [ ]

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