Carbohydrate fluorosulfates

Carbohydrate fluorosulfates

CARBOHYDRATE Preliminary Carbohydrate RESEARCH 331 communication fluorosulfates E. BUNCEL, H.J. JENNINGS, J.K.N. JONES, and Department of Chemist...

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CARBOHYDRATE

Preliminary Carbohydrate

RESEARCH

331

communication fluorosulfates

E. BUNCEL, H.J. JENNINGS, J.K.N. JONES, and Department of Chemistry, Queen’s University. Kingston. Ontario fCa,lada)

I. M. E. THIEL Departamento de Quimica Organica, Facultad de Ciencias Exacras _I’:Varwa!es, Peru Z-72, Buenos Aires (Argentina)

(Received February 17th. 1969)

Study of the carbohydrate chlorosulfates has proven to be of value in synthesis. for example, of chlorodeoxy and of cyclic-sugar sulfate derivatives’.‘, and in elucidating conformational aspects of nucleophilic substitution at secondary carbon atoms of sugar derivatives2y3. These substitutions are characterized by an escecdingly high leaving-group ability of the chlorosulfate moiety, as shown by kinetic studies on a model series of alkyl chlorosulfates4. Fluoro substitution might further enhance this effect and study of carbohydrate fluorosulfates could be correspondingly useful. However, a previous attempt5 to prepare this type of derivative directly by reaction between a sugar calbinol group and sulfuryl tluoride, analogous to the preparation of the chlorosulfates1-3, was unsuccessful. We now report rhe synthesis of some sugar fluorosulfares with several structural modifications: (a) 0S02 F on C-2 (hexopyranose); (b) OSO, F on C-3 (hexofuranose): (c) OSOz F on C-6 (hexopyranose): (d) a derivative having two tluorosuifate moieties, on C-2 and C-3 (hexopyranose). The method used involves the action of silver fluoride on known sugar chlorosulfates. The preparation of the last compound is described in detail. Methyl -L,6-dichloro-4,6-dideoxya-D-salactopyranoside 7,3-dichlorosulfate’” (2.36 g, 0.0054 mole) in methanol solution (100 ml) was treated with silver fluoride (5.4 g, 0.042. mole, AIfa Inorganics, Inc.) in water (20 ml) and the mixture was stirred at room temperature in the dark. Intermittent sampling and chromatographic (t.1.c.) testing for chlorosulfate by the butyl alcohol-aniline-pyridine spray reagent’ showed that reaction was complete after 43 11. Filtration and concentration gave a syrup that was dissolved in chloroform, repeatedly washed with water, and then worked up in the usual manner, to yield methyl 4,6-dichloroA.b-dideosya-D-galactopyranoside 2,3-difluorosulfate as a syrup, [o~]D +I 59.6” (c 1.7, chloroform). Anal.: Calc. for C, HloOsClz F, S2 : C, 31.26; H. 2.55: Cl, 17.92: F, 9.64: S, 16.31. Found: C, 31.43: H. 2.73: Cl, 18.26: F. 9.81: S, 16.03. The n.m.r. spectrum of the product corresponded very closely to that of the reactant, indicating that no skeletal changes had taken place. The i.r. spectrum showed strong absorption at 1460 cm-’ and 1P5 cm-’ _shifted from 1477 cm-’ and 1192 cm-’ compared with the reactant; the observed shifts in the i.r. frequencies correspond to those expected’ for conversion of OSO, CI into 0S02 F. CarbOWf. Rrs.. 10 (1969) 331-332

332

PRELIMINARY

COMMUNICATION

By similar procedures the following fluorosulfates have been prepared from the corresponding chlorosulfates: methyl 3,4,6-trichloro-3,4,6-trideoxy+D-allopyranoside .2-fiuorosulfate, 1,2:5,6diU-isopropylidene-o-D-glucofuranose 3-fluorosulfate, and 1,2:3,4di-O-isopropylidene-o-D-galactopyranose 6-fluorosulfate. The primary fluorosulfate derivative decomposed on standing, precluding characterization by elemental

analysis,

but the former

two fluorosulfates

gave satisfactory

analytical

data.

The relatively slow ionxxchange

process at sulfur observed in these reactions is noteworthy Further studies relating to the synthesis and reactions of the carbohydrate fhrorosulfates are being undertaken, particularly as to their possible use as intermediates in the synthesis of the still difficultly accessible deoxyfluoro sugars.

ACKNOWLEDGhlENTS

We thank the National Research Council of Canada for financial support and the de Investigaciones Cientificas y TCcnicas de la Republica Argentina for a scholarship (to I.M.E.T.). Consejo

National

REFERENCES P. D. Brag, J. K. N. Jones, and J. C. Turner, Can. J. Ckrn., 37 (1959) 1412; J. K. N. Jones, 31. 8. Perry. and J. C. Turner. ibid.. 38 (1960) 1122. (a) H. J. J&&ngs and J. K. N. Jon&, C& J. &wz.. 41 (1963) 1151: (6) ibid., 43 (1965) 3372; (c-) ibid., 43 (1965) 3018. A. G. CottrelI, E. Buncel, and J. K. N. Jones, CZler?z. Zt~d. (London), (1966) 552; Call. J. CIrerrr.. -I4 (1966) 1483; S. S. Ali, T. J. Mepham, I. &I. E. Thiel, E. Buncel, and J. K. N. Jones, Carbolzyd.

5 (1967) 118. E. Buncel and J. P. 1Iillington.

Proc. CJxvn. SOP_, (1964) 406; 43 (1965) 556. K;. \v. Buck and A. B. 1:oster.J. CJzem. Sot., (1963) 2217. G. Crank, ill. SC. Thesis, Queen ‘s University, (1960). E. A. Robinson, Can. J. Chern.. 39 (1961) 247.

Carbohyd.

Rex.. 10 (1969)

Can. J. Chetn., 43 (1965)

547;

331-332

Announcement

A Euchcm

Conference

on the Chemistry

of Carbohydrates

will be held at the

University of Birmingham from 15-l 9 September 1969. Topics to be discussed include applications of physical methods, solvolytic and displacement reactions, and newer methods University

of synthesis.

Further

of Birmingham,

details from Dr. J.M. Webber,

P.O. Box 363,

Birmingham

15.

Department

of Chemistry,

Rex