Studies Of The Cleavages And Stabilities Of Carbohydrate Epoxides And Epimines

• Main Author: Johnson, Curtis Alvin
• Format: Others
• Published: Scholarly Commons 1971
• Subjects: Organic chemistry; Pure sciences; Chemistry
• Online Access: https://scholarlycommons.pacific.edu/uop_etds/2820; https://scholarlycommons.pacific.edu/cgi/viewcontent.cgi?article=3819&context=uop_etds

A novel epoxide ring opening of benzyl 3,4-anhydro-2-benzylox-carbonylamido-2-deoxy-β-D-allopyranoside(I) was affected by phenylboronic anhydride in toluene. One of the products was demonstrated to be benzyl 2-benzyloxycarbonylamido-2-deoxy-4,6-0-phenylboronate-β-D-gulopyranoside. Another product isolated, while not identified, had the properties of an anhydro-sugar different from the starting compound(I). Benzyl 6-0-acetyl-2-benzyloxycarbonylamido-2-deoxy-β-D-allopyranoside(II) also underwent epoxide ring opening in a reaction with phenylboronic acid. An isolated product had the properties of a benzyl 2-benzyloxycarbonyiamido-2-deoxy-D-hexoside different from compounds isolate in the reaction of I with the phenyboronate. This indicated the necessity for an unsubstituted 6-OH group in order for the boron compound to be involved in the ring opening. Supporting this view is the lack of reaction between the blocked benzyl 2,3-anhydro-4,6-0-benzylidene-α-D-allopyranoside and phenylboronic anhydride. The 2,3-epoxide ring of benzyl 2,3-anhydro-4,6-0-benzylidene-α-D-allopyranodie(III) was shown to be remarkably stable in a reaction with boron acetate in nitromethane. The product had retained the 2,3-epoxide ring under conditions that removed the benzylidene group. Trimethylsilyl azide was prepared in good yield in a mild and direct method. The azide was then used to prepare a new, low-melting, compound by dilation of the 6-OH group of I. The epoxide ring remained stable under these conditions The epimine ring of benyl 4,6-0-benzylidene-2,3-dideoxy-2,3-epimino-α-D-allopyranodie(IV) was found to be unreactive with phenylboronate. However IV was deaminated with HNO2 to give the 2,3-unsaturated to give benzyl 4,6-0-benzylidene-α-D-mannopyranoside. The purpose of this study was to test the reactivity of sugar epoxides toward novel, ring-opening reagents. The study is especially concerned with the opening of the epoxide ring of benzyl 3,4-anhydro-2-benzyloxycarbonylamido-2-deoxy-β-D-allopyranoside, which has been found to be quite stable.1 These reagents were also used in a comparative study of the reactivity of epimino rings of sugars. Epimino rings react in a manner analogous to eposice rings. They have also been found to be quite stable in sugars.2,15