6,8-Dithiooctanoic acid

Lipoic acid (6,8-dithiooctanoic acid) was isolated and characterized in 1951 in studies that showed that it was required for the growth of certain bacteria and protozoa. This accomplishment was one of the most impressive feats of isolation in the early history of biochemistry. Eli Lilly and Co., in cooperation with Lester J. Reed at the University of Texas and I. C. Gunsalus at the... 

This approach makes use of bromopropyl phosphine 17 as a key synthon obtained via the reduction of 3-bromopropyl phosphonate with dichloroaluminum hydride [10]. Reaction of bromopropyl phosphine 17 with the dianion of 6,8-dithiooctanoic acid produced the -COOH functionalized P2S2-primary bisphosphine framework 18 in > 80% yields (Scheme 7) [10]. 

Dithiooctanoic acid. See Thioctic acid Dithiophos. See Sulfotepp Dithiophosphoric acid, 0,0 -isobutyl amyl ester, zinc salt. See Zinc dialkyl dithiophosphate Di (thiophosphoric) acid, tetraethyl ester. See Sulfotepp... 

Synonyms ALA 1,2-Dithiolane-3-pentanoic acid 1,2-Dithiolane-3-valeric acid 5-(1,2-Dithiolan-3-yl) valeric acid 6,8-Dithiooctanoic acid... 

The most important chemically established compound is a-lipoic acid, the cyclic disulfide of 6, 8-dithiooctanoic acid. This has been isolated in crystalline form from acid-hydrolyzed liver, and also prepared synthetically. Thioctic acids with the —SH groups in different positions than the 6, 8 carbons have also been prepared. Because of the asymmetry of Ce of the octanoate chain, the compound is optically active the dextro form is believed to be the one biologically active. The synthetic DL-form has only half of the activity of the natural product in certain enzyme reactions. 

The emphasis here is on the properties of glutathione (or cysteine if data for cysteine, but not GSH are available). Dithiols which form cyclic or stabilized disulphide radical anions, such as dithiothreitol (//ireo-l,4-dimercapto-2,3-butanediol) [29-33], or the reduced form of lipoic acid (6,8-dithiooctanoic acid) [15, 34-37], in effect have uncharacteristically high values of to be good models for glutathione. In addition, biological effects may be complicated by thiol/disulphide exchange since these thiols will reduce many disulphides [38-40]. Arenethiyl radicals (e.g. phenylthiyl or derived from 2-mercaptoimidi-azole) are closer to phenoxyl radicals in nature than aliphatic thiyl radicals [41-44]. 

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