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[CONTRIBUTION FROM
THE
NATIONAL INSTITUTE OF ARTHRITIS AND METABOLIC DISEASES, NATIOSAL ISSTITUTES OF HEALTH, PUBLICHEALTHSERVICE]
The Reaction of Certain 1-Thioaldose Derivatives with the Silver Salts of Carboxylic Acids. Synthesis of 1-0-Mesitoyl-a-D-glucopyranose BY
CHRISTIAN PEDERSEN
AND
HEWITTG. FLETCHER, JR.
RECEIVEDNOVEMBER 16, 1959 When treated with silver benzoate in boiling acetonitrile D-glucose diethyl dithioacetal is converted in low yield to 2 - 0 benzoyl-wglucose, isolated as its tetraacetate. A similar treatment of ethyl 1-thio-B-D-glucopyratioside gave, after acetyand 2,3,4,6-tetra-0-acet~l-l-~-benzoyl-~-D-glucose. With silver lation, 1,3,4,6-tetra-0-acetyl-2-O-benzoyl-~~-~-glucose mesitoate in boiling acetonitrile ethyl 1-thio-P-D-glucopyranosidegives l-O-mesitoyl-cu-D-glucopS-ranose and its anomer was established through its conversion to (isolated as the tetraacetate). T h e identity of 1-0-mesitoyl-a-D-glucopyranose ~,3,4,6-tetra-~-acety~-~-~-mesitoyl-cu-~-glucose and to 2-0-mesitoyl-~-~-glucose, both substances which had been prepared in earlier researches.
In earlier work in this Laboratory1 the two ano- product was obtained which paper chromatography iiieric 2,3,4,6-tetra-0-acetyl-l-O-mesitoyl-~-glucoshowed to contain glucose and a t least two other pyranoses2were synthesized. Owing to the relative components. Acetylation led to the isolation in stability of the mesitoyl group, compared to the very low yield (7%) of 1,3,4,6-tetra-O-acetyl-2-0acetyl group, no difficulty was experienced in de- benzoyl-a-glucose (11),a substance which had been acetylating the /3-anomer IX either with methanolic described by Brigl and Zerrweck.lo Thus the reammonia' or sodium methoxide, 1-0-mesitoyl-P-D- activity of 1-ethylthio groups toward silver acylates glucopyranose (IT) being obtained in normal fashion. was demonstrated. The elucidation of the comSubsequently4 the deacetylation of the a-anomer plete mechanism of the transformation awaits VI11 with methanolic ammonia was shown to give further work; doubtless a C1 --*. C1 migration of 2-0-mesitoyl-~-glucose(VII), the relatively inert the benzoyl group is involved. mesitoyl group having migrated to the nearest cisAttention was now turned to the behavior of hydroxyl even under these comparatively mild con- ethyl 1-thio-b-D-glucopyranoside (111) with silver ditions. Such a migration of a 1-0-acylgroup in an benzoate. l 1 Here again, the treatment with silver aldose to a cis position a t carbon two had previously benzoate in hot acetonitrile afforded an amorphous been established by Ness and Fletcher5 who showed product. Acetylation led to the isolation in low that mild alkali (such as aqueous pyridine) readily yield of 1,3,4,6-tetra-0-acetyl-Z-~-benzoy~-a-~-g~uto 2,3,5- cose (11) and 2,3,4,6-tetra-0-acetyl-l-0-benzoyl-Pconverts 1,3,5-tri-O-benzoyl-a-~-ribose tri-0-benzoyl-D-ribose. Other, less clear-cut ex- D-glucose (IV).7,12,13 The formation of these comamples of this type of ester migration are k n ~ w n . ~pounds ,~ suggests that, while a 1-0-benzoyl-b-DIn contrast, 1-0-acylaldoses having a hydroxyl at glucopyranose may be stable under these reaction a t carbon two trans to the substituent a t carbon one conditions, the cis anomer undergoes acyl migra(such as 1-0-benzoy~-(3-~-g~ucopyranose~ and 1-0-tion. With the ester of a sterically hindered acid, benzoyl-a-D-talopyranose*) exhibit the normal sta- having less tendency to migrate, one might expect bility of sugar esters. As far as the present authors to obtain an a-1-ester. Accordingly, ethyl l-thioare aware, no well-established example of a cis-l-0- P-D-glucopyranoside (111) was heated in boiling acylaldose, otherwise unsubstituted, has been re- acetonitrile with silver mesitoate. A crystalline p ~ r t e d . We ~ wish now to describe a new route to mono-0-mesitoy~-D-g~ucose,differing in melting the synthesis of 1-0-acylaldoses which has led to point and rotation from the previously known the synthesis of the cis structure, 1-0-mesitoyl-a-D- mono-0-mesitoy~-D-g~ucoses,was obtained. On glucopyranose. acetylation it was converted to 2.3,4,6-tetra-0In preliminary experiments, D-glucose diethyl acetyl- ~ - 0 - m e S i t O y l - ~ - D - g l U C O S(VIII), e a substance dithioacetal (I) was dissolved in hot acetonitrile which had been made in earlier work' through fusion and the solution treated with an excess of silver of a-D-glucopyranose pentaacetate with mesitoic benzoate. The finely divided white salt partly dis- acid in the presence of zinc chloride. The identity solved, the solution became pale yellow and the ap- of the new monoester as VI was confirmed through pearance of the suspended material changed. After its rearrangement, using methanolic ammonia, to removal of the silver ions and benzoic acid, a sirupy 2-U-niesitoyl-/3-~-glucose(VII). Acetylation of the mother liquor from the treat(1) H . B. Wood, Jr., and H. G. Fletcher, J r , , THISJ O U R N A L , 78, 207 (1956). ment of ethyl 1-thio-B-D-glucopyranoside (111) with (2) 3lesitoyl = 2,4,fi~trimethylbenzoyl, silver mesitoate led to the isolation of 2,3,4,G-tetra-0( 3 ) F. Rlicheel and G. Baum, C h e m Bw., 88, 2020 (1955:. acetyl-1-0-mesitoyl-b-D-glucose (IX); both ano(4) H. B Wood, J r , , and H. G, l'letcher, J r . , Tius J O U R N A I . , 7 8 , rneric 1-0-mesitoyl-D-glucoses (IT and VI) had, 2840 (195ti). f5) R . K . Ness and H G. l'letcher, J r , i b d , 78, 4 7 1 0 (19.jfj). therefore, been formed from the 1-thio glucoside. (fj) R . K. Ness a n d H . G. Fletcher, J r . , i b i d . , 80, 2007 (1958). Applications of this reaction to structural problems ( 7 ) L. Zervas, Bey., 6 4 , 2289 (1931). ( 8 ) H. B. Wood, Jr., a n d H. G. Fletcher, J r ,
T H I S J O U R X A L , 79, (10) P. Brigl and W. Zerrweck, Z. physiol. C h e m . H o f i p e ~ S c r l r i ' s , 3234 (1957). 229, 117 (1934). (9) A possible exception, "a-glucogallin" (1-O~galloyl-a-D-gluco(11) It may be noted t h a t t h e tetraacetate of ethyl I - t h i o - p ~ u pyranose), has been reported by 0. T h . Schmidt and J. Herok [ A x ~ I . , glucopyranoside appeared t o be unattacked when heated in acetonitrile 587, 03 (1954) I. Significantly, these authors report t h a t rr-glucr>gallin with silver benzoate. mutarotate.: in aqueous solutir,n, an observation which mny he r l r r r t < > (12) C;. % e ~ n p l & and ~ I? D. I ~ s z l o IVPV., , 48, 91.5 (19l.X a r v l iiiigratic,ii folI,twwl IIV norins1 aii
