Disulfide spectroscopic data

Treatment of a solution of 2-benzothiazolylthioacetyl hydrazide 386 in ethanol with carbon disulfide in the presence of potassium hydroxide gives the rearrangement product [l,2,4]triazolo[3,4- ]benzothiazole-3-thiol 387 (unreported yield) (Scheme 43). The structure of this compound was confirmed by its analytical and spectroscopic data, and confirmed by unequivocal synthesis from 2-benzothiazolhydrazine 388 under the same experimental conditions <2002MI3, 2002MI4>. 

There have been three reports of the same dimeric disulfide. It was first isolated from an unidentified sponge from Guam and the structure elucidated by analysis of spectral data. The (E,E) stereochemistry of the disulfide (500) was defined by comparing the I3C NMR spectroscopic data with those of the (E,Z)-isomer (501) that was obtained as an unstable minor product [425]. Compound 500 was isolated from a species of Psammaplysilla and was called psammaplin A [426]. It was also isolated from Thorectopsamma xana, collected from the same location in Guam, together with a minor dimeric metabolite bisaprasin (502). Both compounds inhibited growth of Staphylococcus aureus and Bacillus subtilis [427]. Psammaplin A (bisprasin) (500) was later isolated from a Dysidea species of sponge and shown to act on Ca2+-induced Ca2+ release channels of skeletal muscle [428]. 

Oxidation of dialkenyl disulfides gave the stereoisomeric 2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane 5-oxides 36 and 37, which are found in extracts of onion. Further conversion and oxidations afforded a series of various 2,3-dimethyl-5,6-dithiabicyclo[2.1.1]hexane derivatives, which were characterized on the basis of the comparative X-ray structural and NMR and IR spectroscopic data. The 111 NMR peak assignments for 36 and 37 were facilitated by LAOCOON III analyses of these 10 spin systems and by examination of the shifts induced by Eu(fod)3 and d6-benzene (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadione) <1996JA2790>. 

Kishore and Balaramt29l described the spectroscopic characterization of the protected tripeptide Boc-Cys-Ala-Cys-NHMe that was stabilized by an intramolecular disulfide bridge. NMR data confirmed the presence of an 11-membered disulfide loop, which enforced a y-turn conformation. A major limitation of this type of approach is the requirement that two of the three residues in the y-turn must be cysteine and therefore only one functional group can be presented in the turn. 

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