. Author manuscript; available in PMC: 2015 Aug 4.

Published in final edited form as: Chem Commun (Camb). 2014 Aug 4;50(60):8219–8222. doi: 10.1039/c4cc03527e

Table 1.

pK_a values of the amine moiety of 2-substituted thiazolidine/thiazinane-4-carboxylic acids.

Compound	pK_{a exp}, (pK_{a lit})	Compound	pK_{a exp}
	NA,^a (5. 6736)		6.67^b
	5.50,^a (5.3136)		6.85^b
	6.44, (6.19)		7.76

3a and 4a were found to be relatively unstable showing signs of decomposition in aqueous solution during the course of the titration (Fig. S15 and S16, ESI†).

3b and 4b showed no indication of decomposition (Fig. S15 and S16, ESI†)