5028
Macrolide Stereochemistry.' IVe2 On the Total Absolute Configuration of Carbomycin (Magnamycin)3 Sir : Representation I for carbomycin3s4 (Chart IIs is in accord with reports on (a) gross ~ t r u c t u r e , ~ (b) ,~
and (e) provisional specifications for all macrocycle asymmetric centers1' The latter view, derived from recent workings" of a macrolide configurational model'c~'2 (Chart II),I3~l4 has served to call attention to previous specification^'^ 6s:8Ssbregarded as tantamount to "biogenetically exceptional" configurations.
Chart I 0
(mno) II
II
ct
H
TH cH3+H OR
0
I
c"3T..
* a : R=H b : R=Ac
Ib
olefinic geometry,6 (c) stereochemistry of sugar conThis report announces new configurational determinastituents,'bzs-'o (d) certain relative c o n f i g ~ r a t i o n s , ~ J ~tions 6R:SR: 12R: 13s: 15R which substantiate pertinent correlations outlined in Chart I1 and neces( I ) (a) Part I : J . A m . Chem. Soc., 87, 1797 (1965); (b) part 11: sitate revision of the earlier "exceptional" assignibid., 87, 1799 (1965); (c) partIII: ibid., 87, 1801 (1965). (2) (a) For a preliminary account see W. D. Celmer, Abstracts, ments. Thus, only 3R:4S:5S from Chart I1 re152nd National Meeting of the American Chemical Society, New York, main to be tested. It is noted further that carboN. Y., Sept 1966, No. P 47; (b) for macrolide reviews, see M. Berry, mycin could conceivably contain another element of Quart. Rec. (London), 17, 343 (1963), and also ref 11. (3) (a) Magnarnycin is the registered trademark of Chas. Pfizer & chiralitysb (space-handedness) imposed by theoretically Co., Inc., for the antibiotic carbomycin. Two forms, A (Ia) and B possible restricted rotation of the sp2-hybridized (Ib), are described (cy. Chart I and ref 4b,d; chemical conversion of A to B is reported in ref 6 and 7a). (4) (a) F. W. Tanner, A. R. English, T. M. Lees, and J. B. Routien, Antibiot. Chemotherapy, 2, 441 (1952); (b) R. L. Wagner, F. A. Hochstein, I
