Abstract:
Addition of the elements of iodine(I) thiocyanate to alkenes has been achieved using iodine-thiocyanogen. Further evidence in support of the results of an earlier study has been obtained for the occurrence of radical reactions under irradiation by u.v. light. Evidence is presented that iodine(I) thiocyanate is not a major species in solutions of mixtures of iodine and thiocyanogen.
The reactions of vic-iodoisothiocyanates with carbanions have been studied with the aim of synthesising 2-substituted 2-thiazolines and 1,3-thiazolidines suitable for further elaboration to the penam skeleton. In particular, di-t-butyl malonate derivatives of vic-iodoisothiocyanates have been synthesised in high yield by treatment with di-t-butyl sodio-malonate. Cleavage and mono-decarboxylation with trifluoroacetic acid, followed by aluminium amalgam reduction of the resulting 2-thiazolines afforded t-butyl (1,3-thiazolidin-2-yl) acetate derivatives.
Acid-catalysed cleavage of the t-butyl (1,3-thiazolidin-2-yl)-acetates, and of di-t-butyl 2-methyl-2-[rel-(1R,6S,8R)-7-thia-9-azabicyclo[4.3.0]nonan-8-yl]malonate with hydrogen chloride gave the hydrochlorides of the corresponding β-amino acids. Cyclisation using a water-soluble carbodiimide yielded non-functionalised polycyclic β-lactams incorporating the penam nucleus.