4863lonate pathways in H . halobium are identical with those in other organisms.As discussed above, the cryptic stereochemistry involved in the incorporation of glycerol into the membrane lipid of H . halobium was firmly established. In contrast to eubacteria and eukaryotes, it is the sn-C-1 methylene group of 2,3-di-Gphytanyl glycerol that is derived from the sn-C-3 carbon of glycerol and the C-6 carbon of D-glucose. Although stereochemically feasible, a pathway including reduction of ~-glyceraldehyde-3-phosphate can be ruled out, since the present as well as previous studies clearly showed that no hydrogen was lost from either hydroxymethyl group of g l y~e r o l .~,~ Furthermore, the ether-forming reaction is also different from that of 0-alkyl dihydroxyacetone phosphate in mammalian cells?J0 in which a hydrogen of the sn-C-1 methylene group is stereospecifically replaced. Consequently, the most likely mechanism of formation of sn-2,3-0-diphytanyl glycerol in H . halobium apparently includes a unique stereochemical inversion a t the C-2 carbon of glycerol as shown in Scheme I.Acknowledgment. Proton and deuterium N M R spectra were recorded through the courtesy of Dr. M. Uramoto, Institute of Physical and Chemical Research, and Professor H. Set0 and Dr. K. Furihata, the University of Tokyo, to whom we are grateful. (9) Brown, A. The largest [S,M,(SR),]'-molecular aggregate structure reported to date is [E4Mlo(SPh)16]' (E = s, Se; M = Zn, Cd) (l).'
Treatment of a solution of PhSH and NEt3 in acetonitrile with Cd(NO3)2 in acetonitrile and Na2S in methanol, with alternating additions of the latter two reagents, followed by addition of Me4NCl in methanol yields the title dianion as Me4N+ salt in 20% yield.
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