VOLUME 2,3-anhydro

Anhydro-D-glucose, Glucose and Sorbitol Transfer 30 mg of sample, accurately weighed, into a screw-cap vial, and add about 2 mL of pyridine. While flushing the vial with a stream of dry air or nitrogen, heat at 80° to 90° until the solution volume is reduced to 0.2 to 0.5 mL. Add a second portion of pyridine, and repeat the evaporation procedure. Continue as directed in the monograph for Polydextrose. Nickel Determine as directed under Nickel Limit Test, Appendix IIIB. 

On this subject Levene deals adequately with earlier work, much of which was due to his own efforts. Attention has chiefly been focused on the attainment of more refined methods for the characterization and estimation of amino sugars and laterly toward the elucidation of their structure. The whole problem of configurational relationships in the group is closely bound up with the study of anhydro sugars (see S. Peat, this volume, page 37) since such products are produced on deamination of amino sugars, a process which also leads to the added complication of Walden inversion. It is not surprising therefore that the direct mode of attack has not led very far. 

In this volume of Advances, Cerny and Stanek, Jr. (Prague) contribute a comprehensive article on the 1,6-anhydro derivatives of aldohexoses. This class of anhydro sugars, earlier termed the hexosans, constitutes by far the largest class of sugar anhydrides to have been studied. The scope of the topic is now so extensive that the Editors, in view of their earlier practice of limiting chapter size in individual volumes of Advances in the interest of diversification of subject material, were inclined to divide this chapter into two parts, to appear in successive volumes. However, as the latter practice has elicited some unfavorable reaction from readers on previous occasions, it was decided to present the article here in its entirety. The chapter complements previous ones on other classes of anhydro derivatives, in particular, recent ones on anhydrides of the oxirane (epoxide) and 2,5-anhydro (oxolane) types. 

Goodman has reviewed neighboring-group participation in Volume 22 of this Series,366 and this subject will therefore not be discussed comprehensively in the present article. However, Goodman specifically excluded from his review the formation of anhydro sugars by oxide ion displacements, and also the formation of anhydronucleosides ( cyclonucleosides ). These topics will therefore be discussed, together with ring contractions and alkoxyl participations, because most of the literature on these subjects has not been reviewed previously. 

Figure 4. Gel filtration of a pectate lyase degraded pectin. AUA = anhydro-uronic acid content, Ve = elution volume, the eluent was water.

While the isolation of des-base-A as one of the products of the Hofmann reaction has added further support for the structure assigned to methyl-(chano)-dihydroneostrychnidine, yet it is the isomeric des-base, anhydro-methylstrychnidinium-D hydroxide (des-base-D, m.p. 196-197°) that has provided a whole series of new compounds by a novel reaction. Introduction of two hydrogen atoms into des-base-D by catalytic reduction (palla-A solution of 9.0 g. of des-basc-D in 130 cc. of 10% hydrochloric acid is shaken with hydrogen at 17-19° in the presence of palladium-charcoal catalyst. The uptake of hydrogen ceases when 355 cc. of hydrogen (theory 600 cc.) is absorbed. Further addition fails even at 90°. The hot solution is filtered, made ammoniacal, and concentrated under vacuum to one-third its volume. The concentrate, when treated with a solution of 10 g. of sodium iodide in 10 cc. of water, yields a colorless precipitate which is a mixture of methyldihydrostrychnidinium-D iodide and methyldihydrostrychnidinium-A iodide. Repeated fractional crystallization from water yields 8.7 g. of the former (m.p. 325-327°) and 3.2 g. of the latter (m.p. 345-350°). 

It is known that deamination of some readily available amino acids can be performed with nearly quantitative retention of configuration. Based on this conversion, Yamada and co-workers elaborated an ingenious synthesis of o-ribose and D-lyxose starting from L-glutamic acid. The preliminary communication of this work was reported in the first volume of Ais series.Now the full details have been published. In an extension of the application of the unsaturated intermediate (399) for the synthesis of other pentoses, all 2,3-anhydro derivatives (400-403) were prepared. LAH-Reduction of -D-ribo and o-D-lyxo epoxides (400 and 401) afforded, after acetylation, 3-deoxy-pentosides 404 and 405, whereas the same reaction conditions converted fi-D-lyxo a-D-ribo epoxides (402 and 403) into the corresponding 2-deoxy-derivatives (406 and 407). 

AT-Ray Analysis.— A crystallographic study of the anhydro-base of 2,3-dimethylbenzothiazole has confirmed the second of the two structures (52) and (53) that had previously been discussed (see Volume 1, p. 416). 

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