Tetraether bolaamphiphiles

Thompson et al. have developed a few symmetric, tetraether bolaamphiphiles 19a, 19b, with anionic headgroups [48]. The aqueous dispersions of these lipids behave as good mimics of archaebacterial membranes. 

Fuhrhop, J.-H., Liman, U., Koesling, V. (1988). A macrocyclic tetraether bolaamphiphile and an oligoamino a, -dicarboxylate combine to form monolayered, porous vesicle membranes, which are reversibly sealed by EDTA and other bulky anions, J. Am. Chem. Soc., 110 6840. 

Ether linkages in open-chain bolaamphiphiles were obtained in a 20% isolated yield from a,o)-dibromoeicosane with an alcohol in THF containing sodium hydride (Scheme 2.8). The synthesis of macrocyclic tetraethers was unsuccessful. Attempts to reduce macrocyclic lactones with four ester groups via a variety of methods failed. The production of macrocyclic thioacetals from benzaldehyde derivatives and a,to-dithiols was unproblematic and produced quantitative yields (Scheme 2.8). The cyclization of 2,2-thiodiethanol with a,(o-diols in the melt and in the presence of /7-toluenesulfonic acid is an intermediate case. Apolar macrocycles were obtained in 50% yield. 5-(2-hydroxyethyl)thiiranium ions are presumably formed as reactive intermediates during the ether formation steps. The sulphur atom was oxidized to the... 

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