5136
Although the detailed conformation of
our conformational analysis to be reliable.
Finally, the 9R alcohol derivative (4) was converted to maridonolides in several steps.2b)
A is not clear yet, the above successful results show
R e f e r e n c e s
and
N o t e s
1)
Chiral synthesis of polyketide derived natural products. 36. For part 35 see
T. Matsushima, O. Yonemitsu, H. Goto, and E. Osawa, Chem. Pharm. Bull., in press.
a) N. Nakajima, K. Uoto, O. Yonemitsu, Heterocycles., 31, (1990) ; b) N. Nakajima, T,
: N. Nakajima,
2)
5
Matsushima, O. Yonemitsu, H. Goto, and E. Osawa, J. Org. Chem., 55, 1129 (1990) ; c) N.
Nakajima, K. Uoto, and O. Yonemitsu, Chem. Pharm. Bull., 39, 64 (1991).
H. Goto, and E. Osawa, J. Am. Chem. Soc., 111, 8950 (1989).
3)
4)
5)
6)
Maridomycins : M. Muroi, M. Izawa, M. Asai, T. Kishi, K. Mizuno, J. Antibiot., 26, 199 (1973).
2
gave broad unresolved peaks at 100°C (in DMSO-d6).
At the first development at room temperature, was detected as two spots. On standing for
2
15 minutes at room temperature after the first development, the interconversion between
two conformers occured, and each spot appeared as two spots at the second development.
On the other hand, at -35°C, the initial two spots remained unchanged at the second
development after standing for
Since reliable MM calculation for epoxyenones is still impossible, the NMR studies are
very important. For the conformational studies of macrocyclic systems in solution, see a)
1 week.
7)
:
A. B. Smith III, J. L. Wood, C. J. Rizzo, G. T. Furst, P. J.. Carroll, J. Donhue, and S. Omura, J.
Org. Chem., 55, 1133 (1990) ; b) T. H. Keller, and L. Weiler, J. Am. Chem. Soc., 112, 450
(1990) ; c) i d e m , Tetrahedron Lett., 31, 6307 (1990) ;. d) I. Paterson, and D. J. Rawson,
Tetrahedron Lett., 30, 7463 (1989) ; e) T. H. Keller, E. G. Neeland, S. Rettig, J. Trotter, and L.
Weiler, J. Am. Chem. Soc., 110, 7858 (1988) ; f) E. Neeland, J. P. Ounsworth, R. J. Sims, and L.
Weiler, Tetrahedron Lett., 28, 35 (1987) ; g) J. R. Everrett, and J. W. Tyler, J. Chem. Soc.
Perkin Trans. 2, 1659 (1987) ; h) E. Vedejs, W. H. Dent, lII, D. M. Gapinski, C. K. McClure, J.
Am. Chem.Soc., 109, 5437 (1987) ; i) S. K. Arora, and A. M. Kook, J. Org. Chem., 52, 1530
(1987) ; j) L. Cellai, S. Cerrini, A. Serge, M. Brufani, W. Fedli, and A. Vaciago, J. Org. Chem.,
47, 2652 (1982) ; k) W. C. Still, and I. Galynker, Tetrahedron, 37, 3981 (1981).
8)
3
was easily obtained from the degradation product of josamycin (leucomycin A3) via
several conventional reactions including epoxidation, and gave more clearly resolved 1H
NMR peaks.Tor the degradation of josamycin, see : K. C. Nicolaou, S. P. Seitz, M. R. Pavia, J.
Am. Chem. Soc., 103, 1222, 1224 (1981).
9)
The dihedral angles were estimated by reference to the Karplus equation, except for the
angle of the olefin proton ( H l l ) and epoxy ring proton (H12), which was determined in
accordance with the following report. F. Jansen, and C. S. Foote, J. Am, Chem. Soc., 109,
6376 (1987).
10)
1
has several conformers in solution mainly caused by easy rotation of the dienone
without unfavorable transannular interaction, and their interconversion occurs rapidly
and can be detected only by NOE measurements. For the details, see ref. 2b.
(Received in Japan 7 May 1991)