5795
sequitor).) The carbon magnetic resonance spectrum of unlabeled streptovaricin D (1) showed peaks for the expected 40 carbon atoms. Relevant carbon atom signals were assigned (Table 11) with the help of the Table II. Important Carbon Magnetic Resonance Peaks for Streptovaricin D (1) Carbon atom”
c-1 c-3 c-5 c-7 c-9 c-11 C-13 C-15 C-17 C-19 c-21
6Cb
169.4 134.7 144.1 83.6 77.6 73.4d 70. 4d 153.6 169.0 159.6 188.7
Re1 enrichmentc 0.7
0.0 1.3 0.8 1.1
1.0 0.8 1.1 0.0 1.3 0.0
Numbering for 1 is shown in Figure 1. b Ppm from TMS; CDZCl2= 53.80. Calculated by measuring peak heights in the spectrum of enriched streptovaricin D relative to the height (arbitrarily assigned the value 1.00) of the peak a t 153.6 ppm (the tallest of these peaks in the unenriched spectrum), then dividing those relative heights by the relative heights of the same peaks (calculated the same way, from an assigned value 1.00 for the peak a t 153.6 ppm) in the natural abundance spectrum. The relative enrichments, which of necessity are rough approximations, have been May be interchanged. normalized so their sum is 8.0.
from methionine. The origin of the benzenoid aromatic ring and the quinone carbonyl carbon ((2-21 through C-27) remains to be established. Experiments along these lines are in progress. Acknowledgments. This work was supported by Public Health Service Grants AI 01278 and AI 04769 from the National Institute of Allergy and Infectious Diseases and in part by Contract NIH-NCI-C-72-3208 from the Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Department of Health, Education, and Welfare. We thank Mr. Robert Thrift for the 13Cnmr spectra, obtained on a spectrometer purchased with an instrumentation grant from the National Science Foundation, Mr. Joseph Wrona for the isotope ratio mass spectra, and Dr. Robert F. Nystrom for assistance with the synthesis of I3C-labeled propionate. Supplementary Material Available. A more detailed description of assigned chemical shifts will appear following these pages in the microfilm edition of this volume of the journal. Photocopies of the supplementary material from this paper only or microfiche (105 X 148 mm, 20X reduction, negatives) containing all of the supplementary material for the papers in this issue may be obtained from the Journals Department, American Chemical Society, 1155 16th St,, N.W., Washington, D . C. 20036. Remit check or money order for $3.00 for photocopy or $2.00 for microfiche, referring to code number JACS-73-5793.
carbon magnetic resonance spectra of other streptovaricins; of standard chemical shift data;7 and of Barry Milavetz, Katsumi Kakinuma, Kenneth L. Rinehart, Jr.* complete, off resonance, and specific p r ~ t o n ~ d e c o u p l i n g . ~ Roger Adanis Laboratory, Unicersity of Illinois Urbana, Illinois 61801 The carbon magnetic resonance spectrum of 13Clabeled streptovaricin D showed eight clearly enriched James P. Rolls, Willard J. Ha& peaks of similar intensity for C-I, C-5, C-7, C-9, (2-11, The Upjohn Company C-13, C-15, and C-19. Most important, the present Kalamazoo, Michigan 49000 data establish that the amide-head pathway (path a) is Receiced April 24, 1973 that followed, since the amide carbon (C-I) and C-5 are labeled by propionate carboxyl but C-3 is not. That one of the ring carbons (C-19) is labeled by proCollision-Induced Negative Ion Mass Spectrometry’ pionate carboxyl implies a continuous sequence of Sir : propionate and acetate units leading from (2-20 through C-1. We assume acetate (or malonate) as the origin of We have previously shown that certain classes of C-3 and C-4 and of C- 17 and C- 18. organic compounds will accept an electron to produce The quinone carbonyl (C-21) is unlabeled by promolecular anions which may then undergo characteristic pionate, as are C-26 and C-24, the carbons adjacent -~ decompositions. 2 , 3 It has been d e m ~ n s t r a t e d ~that to the remaining methyl group at C-25.lo The lack of molecular anions may be formed by secondary electron a methyl at the carbon in rifamycin3 corresponding capture under these condition^,^ and it follows that our to C-25 suggests that our C-25 methyl group comes spectra may be produced by the decomposition of molecular anions with thermal or near thermal energies. (7) (a) L. F. Johnson and W. C. Jankowski, “Carbon-13 NMR SpecThis has been substantiated for the case of the 2-aryltra,” Wiley-Interscience, New York, N. Y., 1972; (b) J. B. Stothers, “Carbon-1 3 NMR Spectroscopy,” Academic Press, New York, N. Y., 1,3-0xathianes.~ 1972; (c) G. C. Levy and G. L. Nelson, “Carbon-13 Nuclear Magnetic There are many molecular anions which do not deResonance for Organic Chemists,” Wiley-Interscience, New York, compose, and there are some functional groups which N. Y., 1972. (8) K. L. Rinehart, Jr., M. L. Maheshwari, F. J. Antosz, H. H. show no fragmentation in the negative mode. It is Mathur, I
