Ethylene-oxide ring

Anhydro-D-glucose results from the action of anhydrous ammonia on l-chloro-2-trichloroacetyl-D-glucose triacetate (Brigl s compound73 8) and the preferential formation of an ethylene oxide ring is undoubtedly due to the lability of the trichloroacetyl group in position 2. 

Ethylene oxide rings have as yet been introduced only at the ends of hexitol molecules by hydrolysis of suitable substituents attached to primary carbon atoms, so no question of Walden inversion has arisen. 

G. Miscettaneous Nwdeopkilic Additions (1) Azide ion. The ready cleavage of ethylene oxide rings by N. ion is in acoordanoe with its recognized nucleophilic character. Alllums-Ii so far limited to three,6 8-127 -1778 publications devoted to this reaction have explored the behavior of a wide assortment of epoxides. Jt. is customary to characterize 0-azido alcohol obtained on treatmml of epoxides with aqueous sodium azide by reduction to /1-atnirm aa-o-hok.iwo. ins aa shown in Eq. (896). 

Perhaps of interest at this point are certain studies involving rupture of the ethylene oxide ring by pyrdysiB or photolysis. 

In this respect, the aromatic component of such Friedel-Crafts condensation may be considered to function as a nucleophilo, in which w-electrona attack the aluminum chloride-coordinated ethylene oxide ring. 

The product that is obtained experimentally depends upon the structure of the molecule containing the ethylene oxide ring. By using appropriate reagents for the cleavage, however, it is possible to obtain either 2- or 3-substituted derivatives which can be converted directly to 2-or 3-desoxysugar derivatives. The protection afforded by the gly-cosidic residue increases the possibility of improved overall yields of the desoxysugars. 

From these experiments it appears that the splitting of the ethylene oxide ring of methyl 2,3-anhydro-4,6-benzylidene-hexosides occurs in the same way both with sodium methoxide and sodium thiomethoxide (sodium methylmercaptide) and reaction occurs according to the follow-... 

Similarly, if sodium hydroxide is used for rupture of this kind of ethylene-oxide ring, the products are as follows ... 

Opening of the ethylene oxide ring occurred immediately upon adding catalyst. 

The mechanism of Grignard addition to oxetane is the same as the mechanism of Grignard addition to epoxides, described in Section 18.6. The reaction proceeds at a reduced rate because oxetane is less reactive than ethylene oxide. The four-membered ring oxetane is less strained, and therefore more stable, than the three-membered ethylene oxide ring. 

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