Amphidinolide relative stereochemistry

Amphidinolides B6 (2f) and B7 (2g) have been isolated from a marine dinoflagellate Amphidinium sp. (strain HYA002), which was isolated from the marine acoel flatworm Amphiscolops sp. collected off Sunabe beach, Okinawa. The planer structures of amphidinolides B6 (2f) and B7 (2g) were elucidated from the detailed analyses of 2D NMR spectra. Relative stereochemistries of these macrolides were deduced from NOESY data... 

Amphidinolide C (3a) is a 25-membered macrolide isolated from Amphidinium sp. (strain Y-5), possessing an s-cis and an s-trans Aienes, two fxo-methylenes, two tetrahydrofuran rings, a 1,2-diol, and four branched methyl groups. The relative stereochemistry of the C-l-C-8 and C-20-C-23 portions has been elucidated by NOESY correlations of amphidinolide C (3a) and its 7,8-0-isopropylidene derivative. Application ofthey-based configuration analysis revealed the etythro-m xion for the C-12-C-13 bond and the relation for the C-23—C-24 bond. The absolute... 

Amphidinolide F (6) is an analog of amphidinolide C (3a), isolated from Amphidinium sp. (strain Y-26) obtained from a flatworm A magniviridiscoWecx A at Zampa, Okinawa. The structural difference between amphidinolides F (6) and C (3a) was found in the length of the alkyl side chain. Since the H and C chemical shifts of amphidinolide F (6) were close to those of amphidinolide C (3 a), the relative stereochemistry of 11 chiral centers in amphidinolide F (6) was suggested to be the same as that of amphidinolide C (3a). 

Amphidinolide Q (16), C21H34O4, is a 12-membered macrolide possessing four branched methyl groups, an a ti-methylene, and a ketone carbonyl, isolated from the marine dinoflagellate Amphidinium sp. (strain Y-5). The relative stereochemistry of amphidinolide Q (l) was elucidated on the basis of -based configuration analysis method and NOESY correlations. The absolute configurations of amphidinolide (16) were concluded to he AR, 7R, 9S, 115, and 135 by application of the modified Mosher s method to amphidinolide 0 (16) and the linear methyl ester derivatives of amphidinolide... 

Amphidinolide V (21) is a 14-membered macrolide possessing four dxo-methylenes and an epoxide, isolated from the marine dinoflagellate Amphidinium sp. (strain Y-5). The relative stereochemistry of amphidinolide V was deduced from the combination of the molecular mechanics calculation and the analyses of H- H coupling constants and NOESY data. Recently, a total synthesis of the proposed structure of amphidinolide V (21) has been achieved by Fiirstner group (Scheme 6). Comparison of the NMR data and CD spectrum of the... 

Ishibashi, M Takahashi, M., and Kobayashi, J. (1995) Amphidinolides O and P, novel 15-membered macrolides from the dinoflagellate Amphidinium sp. analysis of the relative stereochemistry and stable solution conformation. J. Org. Chem., 60, 6062-6066. 

---