COMPLETE RELATIVE STEREOCHEMISTRY OF MAITOTOXIN

By addressing the relative stereochemistry of the four acyclic portion s via organic synthesis, the complete relative stereochemistry of mait otoxin (MTX) has been established as 1B. The relative stereochemistry of the C.1-C.15 portion was elucidated via a two-phase approach: (1) t he synthesis of the eight diastereomers possible for model C, represen ting the C.1-C.11 portion, and the eight diastereomers possible for mo del DI representing the C.11-C.15 portion, and the comparison of their proton and carbon NMR characteristics with those of MTX, concluding t hat 9 and 35 represent the relative stereochemistry of the correspondi ng portions of MTX: (2) the synthesis of the two remote diastereomers 51 and 52, and comparison of their proton and carbon NMR characteristi cs with those of MTX, concluding that 51 represents the relative stere ochemistry of the C.1-C.15 portion of MTX. The relative stereochemistr y of the C.35-C.39, C.63-C.68, and C.134-C.142 acyclic portions was es tablished via (1) the synthesis of the 8, 8, and 16 diastereomers poss ible for models E, F, and G, respectively, and (2) the comparison of t heir proton and carbon NMR characteristics with those of MTX, concludi ng that 81, 117, and 187, respectively, represent the relative stereoc hemistry of the corresponding portions of MTX. Some biogenetic conside rations have been given to speculate on the absolute configuration of MTX. The vicinal proton coupling constants observed for models 54, 81, 117, and 187 were used to elucidate their preferred solution conforma tion. Assembling the preferred solution conformations found for the fo ur acyclic portions allows one to suggest that the approximate global conformation of MTX is represented by the shape of a hook, with the C. 35-C.39 portion being its curvature. MTX appears to be conformationall y relatively rigid, except for conformational flexibility around the C .7-C.9 and C.12-C.14 portions. On the basis of the experimental result s gained in the current work, coupled with those in the AAL-toxin/fumo nisin area, it has been pointed out: that the structural properties of 51, 81, 117, 187 and their diastereomers are inherent to the specific stereochemical arrangement of the small substituents on the carbon ba ckbone and are independent from the rest of the molecule. Thus, it has been suggested that each of these diastereomers has the capacity to i nstall a unique structural characteristic through a specific stereoche mical arrangement of substituents on the carbon backbone, and that fat ty acids and related classes of compounds may be able to carry specifi c information and serve as functional materials in addition to structu ral materials.