Proof of Constitution

The configuration of the penturonic acid LV was not however conclusively proved to be that of n-xylose and consequently this experiment is not determinative in regard to the configuration, as distinct from constitution, of 3,6-anhydro-D-glucose. 

When the closure of the furanoside ring is not possible, as in the 2,4-dimethyl derivative of LVI (there being no longer a hydroxyl group available on C4), then non-aqueous acid simply catalyzes the inter-conversion of the a and )3 isomers of the methyl n-pyranoside. The 

We may, perhaps, summarize this argument in the following terms. 

It is to be expected, on these grounds, that the predominating component of the mutarotation equilibrium of 3,6-anhydro-glucose will be 

6-anhydro-glucofuranose whereas that of 3,6-anhydro-galactose will be the open-chain form. Neither will include pyranose forms. 

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The rate of iodine formation depends on the degree of A"-substitu-tion. Compounds which are unsubstituted on both the iV-atoms (35) and those wdth a single A -substituent (43) liberate instantly the calculated quantity of iodine in the cold. However, the 1,2-disubstituted diaziridines (44) need brief heating with the acid iodine solution they then give 95-100% of the calculated iodine. " This effect of substitution is so well defined that it can be used for a proof of constitution. The diaziridino-triazolidincs (37) prepared from aldehydes, ammonia, and chloramine give complete iodine liberation only on heating. Thus the structure 57 which is isomeric with 37 can be eliminated. ... 

In this article, the authors have endeavored to summarize the methods of synthesis and the proofs of constitution of all the known methyl ethers of D-glucopyranose and D-glucofuranose. Acyclic glucose ethers are not considered in this review. Later articles will deal with monosaccharides other than glucose. It has not been possible to discuss in full all the reactions involved, but to offset this disadvantage the bibliography has been made as complete as possible and tables have been compiled of the physical properties of the methyl-D-glucoses and of their more important derivatives. 

Proof of Constitution.—Very little reliable evidence regarding the position of the ether group in 2-methyl-D-glucose is available from the methods of synthesis outlined above. In some cases9 1013 the structures... 

Proof of Constitution.—Schinle43 suggested that the methylglucose, formed together with 2-methyl-D-glucose from D-glucose dibenzyl... 

Proof of Constitution.—From the steps in its synthesis from methyl 3-tosyl-2,4,6-triacetyl-jS-D-glucopyranoside, Reeves, Adams and Goebel88 tentatively postulated that the crystalline product was methyl 2,4-di-methyl-6-D-glucopyranoside. They exercised commendable caution,... 

Proof of Constitution.—The. later samples of this dimethylglucose have all been shown to have the same melting point and equilibrium rotation in aqueous solution as Bell s original specimen,99 which itself... 

Proof of Constitution.—Reference to Table XII will show that all of the methods mentioned above as being suitable for the synthesis of 4,6-dimethylglucose have been correlated by means of crystalline derivatives. If the tosyl, benzyl and nitrate radicals can be regarded as being non-migratory (and there is no evidence to the contrary) then the course of the synthesis from 4,6-acetals (the constitution of which has been proved by their conversion into 2,3-dimethyl-D-glucose) leaves no doubt that the methyl groups occupy positions 4 and 6. 

Proof of Constitution.—2,3,4-Trimethyl-D-glucose has not been isolated in a crystalline form and comparisons have been confined to crystalline derivatives, usually the methyl /3-D-glucoside. It is therefore appropriate at present to survey the evidence upon which the characterization of the /3-glucoside, rather than the free sugar, is based. 

Proof of Constitution.—The method of synthesis from methyl 6-trityl-ajS-D-glucofuranoside furnished strong evidence that the trimethyl-D-glucose isolated by Smith121 was substituted at positions 2, 3 and 5. This conclusion was confirmed by the observations (a) that the trimethyl-gluconolactone, produced when the sugar was oxidized with bromine... 

Proof of Constitution.—The definitive synthesis of this crystalline trimethylglucose from 2,3-dimethyl-D-glucose served only to confirm the structure, which had already been assigned to the same compound derived by methylation and hydrolysis from natural D-glucose polymers. 

Proof of Constitution.—Since 2,4,6-trimethyl-a-D-glucose is similar, both in its melting point and equilibrium rotation, to its more common... 

Proof of Constitution.—Since the crystalline a- and 8-forms of 3,4,6-trimethyl-D-glucose, isolated by Sundberg and coworkers,28 were each obtained by hydrolysis of methyl 3,4,6-trimethyl-/3-D-glucopyrano-side,82,154 the proof of the constitution of this glucoside obviously played an important part in the characterization of the trimethylglucose itself. Unfortunately, there is no such crystalline reference compound to correlate the earliest samples of sirupy 3,4,6-trimethyl-D-glucose157,168 with the crystalline specimens isolated by Sundberg and coworkers. 

Proof of Constitution.—Irvine and his school20,160,163 were not slow to recognize that the new trimethylglucose, prepared by them from iso-propylidene-D-glucose, a compound not then characterized, differed from the normal series of glucose derivatives in the extreme ease of its oxida-... 

An ingenious proof of constitution of styracitol has been devised by Zervas and Papadimitriou. They prepared the 6-tosyl tribenzoyl derivative of styracitol and from it the 6-iodo-6-desoxy derivative, which on treatment with silver fluoride gave a compound possessing a double (27) L. Zervas and Irene Papadimitriou, Ber., 78, 174 (1940). 

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