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Mass-spectrometric investigations of peracetates of unsaturated carbohydrates, anhydrodeoxyalditols, and a branched-chain sugar
61
MASS-SPECTROMETRIC INVESTIGATIONS OF PERACETATES OF UNSATURATED CARBOHYDRATES, ANHYDRODEOXYALDITOLS, AND A BRANCHED-CHAIN SUGAR ALEX ROSENTHAL Department of Chemistry, The University of British Columbia, Vancower, B. C. (Canada)
(Received March 12th, 1968) ABSTRACT
The mass spectra of a number of peracetates of unsaturated (carbon-carbon double bond) monosaccharides, anhydrodeoxyalditols, and a branched-chain monosaccharide are presented in tabular form. A detailed interpretation of the fragmentation processes undergone by these molecules is presented. The unsaturated carbohydrates are shown to be intermediates in the breakdown of hexose peracetates. The evidence strongly indicates that the stereochemistry of some anhydrodeoxyalditol peracetates can be determined by mass spectrometry. Mass spectrometry is also a useful technique for indicating
the position
of the branchedchain
on a carbohydrate,
but not its
stereochemistry. The proposed fragmentation processes are supported by the spectra of some isotopically labelled compounds. INTRODUCTION
During the past few years, the usefulness of mass spectrometry as a technique for the determination of structure of the acetates of pentoses and hexoses has been investigated r- 3. Fragmentation patterns were suggested that were supported by the spectra of isotopically labelled compounds, mainly esters of acetic-d, acid. In addition, the spectra of l&anhydrohexopyranose peracetates (some labelled) have been reported4. Although evidence was presented for the possibility of distinguishing furanoses from pyranoses, and of deoxy aldoses from normal aldoses, epimers could not be differentiated. Implicit in the interpretation of the spectra of the peracetates was the assumption that unsaturated carbohydrates (formed by initial expulsion of acetic acid from the parent molecule) constitute important intermediates in the fragmentation pattern. In recent reviews’s6 dealing with the mass spectra of carbohydrates, the authors have emphasized the. importance of the unsaturated carbohydrates in the breakdown of tbe peracetates. Surprisingly, no investigation of the mass spectra of unsaturated carbohydrates, per se, has so far been reported. In this communication are reported the results of an investigation dealing with the mass spectra of peracetates of unsaturated (containing carbon-carbon double bonds) carbohydrates, anhydrodeoxyalditols (some labelled), and one branchedchain (also labelled) aldose. The main mass-peaks, and their relative abundance, of the various peracetates are given in Table I. Carbohyd: Res.. 8 (1968) 61-71
MASS SPECTRA OF SUGAR
DERIVATIVES
71
pen&acetate also exhibits peaks at 169 and 229 (but not at 288, due to elimination of 102 mass units), it might be argued that this sequence does not establish the con.~ figuration at C-3 of compound 10. EXPERIMENTAL
Mass Spectra. - The spectra were determined with an A.E.I.-M. S.9 mass spectrometer, equipped with a direct inlet-probe; ionizing potential 70 eV; temperature of the ion source 150”. The sample (N 0.5 mg) was sublimed directly from a ceramic rod into the ion chamber. ACKNOWLEDGMENTS
The author gratefully acknowledges financial assistance: from the National Cancer Institute of the National Institutes of Health (Research Grant CA-08382), and from the National Research Council of Canada. REFERENCES 1 K. BIEMANN, D. C. DE JONGH, AND H. K. SCI-INOES,J. Amer. Chem. SOC., 85 (1963) 1763. Ann., 667 (1963) 183. 2 K. HEYNS AND H. Sm, 3 K. HEYNS AND D. M-R, Terrnhedron Lerr., (1966) 6061. 4 K. HEYNS AND H. SCHARMANN, Chem. Bet-., 99 (1966) 3!61. 5 H. BUJXXKIEWICZ, C. DJERASSI,AND D. H. WILLIAMS, Structtue Elucidation of Natural Products by Mass Spectrometry, Vol. 2, HoIden-Day, San Francisco, Calif., 1964, pp. 203-240. 6 N. K. KOCFIETKOV AND 0. S. Cr-nz~ov, Adcan. Carbohyd. Chem., 21 (1966) 21. 7 A. ROSENTHAL AND J. N. C. WHME, Can. J. Chem., in press. 8 R. U. LEMIEIJX, D. R. LINEBACK, M. L. WOLFROM, F. B. MOODY, E. G. WAL&E, ANZ F. KOMITSKY, JR., L Org. Chem., 30 (1965) 1092. 9 K. MAUEIZ AND H. Mm, Ber., 60 (1927) 1316. 10 B. H ELFERICH, E-N. MULCAHY,AND H. ZIEGLER, Chem.Ber., 87(1954)233. 11 A. ROSENTHAL AND H. J. KOCH, Can. % Chem., 43 (1965) 1375. AND D. AJ3SON, Carbohyd. Res., 3 (1966) 112. 12 A. RoAND H. J. KOCH, .i. Amer. Chem. Sot., 90 (1968) 2181. . 13 A. Ram Carbohytf. Res., 8 (1968) 61-71
MASS-SPECTROMETRIC INVESTIGATIONS OF PERACETATES OF UNSATURATED CARBOHYDRATES, ANHYDRODEOXYALDITOLS, AND A BRANCHED-CHAIN SUGAR ALEX ROSENTHAL Department of Chemistry, The University of British Columbia, Vancower, B. C. (Canada)
(Received March 12th, 1968) ABSTRACT
The mass spectra of a number of peracetates of unsaturated (carbon-carbon double bond) monosaccharides, anhydrodeoxyalditols, and a branched-chain monosaccharide are presented in tabular form. A detailed interpretation of the fragmentation processes undergone by these molecules is presented. The unsaturated carbohydrates are shown to be intermediates in the breakdown of hexose peracetates. The evidence strongly indicates that the stereochemistry of some anhydrodeoxyalditol peracetates can be determined by mass spectrometry. Mass spectrometry is also a useful technique for indicating
the position
of the branchedchain
on a carbohydrate,
but not its
stereochemistry. The proposed fragmentation processes are supported by the spectra of some isotopically labelled compounds. INTRODUCTION
During the past few years, the usefulness of mass spectrometry as a technique for the determination of structure of the acetates of pentoses and hexoses has been investigated r- 3. Fragmentation patterns were suggested that were supported by the spectra of isotopically labelled compounds, mainly esters of acetic-d, acid. In addition, the spectra of l&anhydrohexopyranose peracetates (some labelled) have been reported4. Although evidence was presented for the possibility of distinguishing furanoses from pyranoses, and of deoxy aldoses from normal aldoses, epimers could not be differentiated. Implicit in the interpretation of the spectra of the peracetates was the assumption that unsaturated carbohydrates (formed by initial expulsion of acetic acid from the parent molecule) constitute important intermediates in the fragmentation pattern. In recent reviews’s6 dealing with the mass spectra of carbohydrates, the authors have emphasized the. importance of the unsaturated carbohydrates in the breakdown of tbe peracetates. Surprisingly, no investigation of the mass spectra of unsaturated carbohydrates, per se, has so far been reported. In this communication are reported the results of an investigation dealing with the mass spectra of peracetates of unsaturated (containing carbon-carbon double bonds) carbohydrates, anhydrodeoxyalditols (some labelled), and one branchedchain (also labelled) aldose. The main mass-peaks, and their relative abundance, of the various peracetates are given in Table I. Carbohyd: Res.. 8 (1968) 61-71
MASS SPECTRA OF SUGAR
DERIVATIVES
71
pen&acetate also exhibits peaks at 169 and 229 (but not at 288, due to elimination of 102 mass units), it might be argued that this sequence does not establish the con.~ figuration at C-3 of compound 10. EXPERIMENTAL
Mass Spectra. - The spectra were determined with an A.E.I.-M. S.9 mass spectrometer, equipped with a direct inlet-probe; ionizing potential 70 eV; temperature of the ion source 150”. The sample (N 0.5 mg) was sublimed directly from a ceramic rod into the ion chamber. ACKNOWLEDGMENTS
The author gratefully acknowledges financial assistance: from the National Cancer Institute of the National Institutes of Health (Research Grant CA-08382), and from the National Research Council of Canada. REFERENCES 1 K. BIEMANN, D. C. DE JONGH, AND H. K. SCI-INOES,J. Amer. Chem. SOC., 85 (1963) 1763. Ann., 667 (1963) 183. 2 K. HEYNS AND H. Sm, 3 K. HEYNS AND D. M-R, Terrnhedron Lerr., (1966) 6061. 4 K. HEYNS AND H. SCHARMANN, Chem. Bet-., 99 (1966) 3!61. 5 H. BUJXXKIEWICZ, C. DJERASSI,AND D. H. WILLIAMS, Structtue Elucidation of Natural Products by Mass Spectrometry, Vol. 2, HoIden-Day, San Francisco, Calif., 1964, pp. 203-240. 6 N. K. KOCFIETKOV AND 0. S. Cr-nz~ov, Adcan. Carbohyd. Chem., 21 (1966) 21. 7 A. ROSENTHAL AND J. N. C. WHME, Can. J. Chem., in press. 8 R. U. LEMIEIJX, D. R. LINEBACK, M. L. WOLFROM, F. B. MOODY, E. G. WAL&E, ANZ F. KOMITSKY, JR., L Org. Chem., 30 (1965) 1092. 9 K. MAUEIZ AND H. Mm, Ber., 60 (1927) 1316. 10 B. H ELFERICH, E-N. MULCAHY,AND H. ZIEGLER, Chem.Ber., 87(1954)233. 11 A. ROSENTHAL AND H. J. KOCH, Can. % Chem., 43 (1965) 1375. AND D. AJ3SON, Carbohyd. Res., 3 (1966) 112. 12 A. RoAND H. J. KOCH, .i. Amer. Chem. Sot., 90 (1968) 2181. . 13 A. Ram Carbohytf. Res., 8 (1968) 61-71