Communications to the Editor 1615 our ester with the one prepared by him from digoxigenin. He reported [private communication] that the melting points were identical and that the melting point of a mixture was not depressed. He has also supplied the specific rotation of his ester, [ ]24 ß + 45.6 ± 3°; [a]24D + 38.9 =*= 3°( 1.183% in methanol).The esters of three acids derived from digoxigenin have now been compared with the corresponding esters of known structure.The resultsshow that digoxigenin has a hydroxyl group at C-12, the steric arrangement of which is opposite to that of the corresponding hydroxyl group of desoxycholic acid. A similar steric arrangement of the hydroxyl group at C-12 is present in the alagodesoxycholic acid described by Kishi [Z. physiol. Chem., 238, 210 (1936)].

It is the purpose of the present paper, first, to describe the behavior of certain ketonic derivatives of thio ethers which are somewhat remarkably labile toward alkali, and, afterward, to point out a probable relation between the behavior of these compounds and the problem of "labile sulfur" in materials of biological interest.Generally speaking, the thio ethers, RSR', are very stable toward all hydrolytic agents. Even the mercaptans of hydrocarbon radicals are quite stable toward acids and alkalies. Recently Billheimer and Reid1 have shown that certain aliphatic mercaptans, when heated for two hours at 260°with 3 N alkali, are only partially hydrolyzed, and these results may perhaps be taken as typical. Vorlánder2 found, not unexpectedly, that triphenylmethyl mercaptan was rather readily hydrolyzed.Really striking lability of the single bond8 between carbon and divalent sulfur, however, is to be found only in derivatives containing other substituents, suitably located, and of these the most effective appears to be the keto group.The -keto derivatives, RCOCH2SR', show in some cases considerable instability of the sulfur-carbon bond, particularly toward alkaline and reducing reagents, and it is of interest that no compound of the type RCOCH2SH appears to have been isolated in a state of purity. The hydrolytic splitting of such compounds seems, however, to have little relation to the common reactions of biological sulfur compounds, as it is frequently, if not generally, attended by the oxidation of the sulfur4 and its replacement by hydrogen.Particular attention must be paid, however, to the /3-keto sulfides, RCH(SR')CH2COR". A number of these compounds have been made, chiefly by Ruhemann6 (see also Posner6). The reaction involved is the 1 Billheimer and Reid, This Journal, 52, 4338 (1930).2 Vorlánder and Mittag, Ber., 46, 3450 (1913). 3 The thio acids and their esters, as well as thiourea derivatives, are substances, the hydrolysis of which is well known and fairly well understood. They are expressly omitted from the present discussion.

No abstract

No abstract

No abstract