title: Dirhodium(II) tetraacetate catalysed reactions of diazo thioamides: isolation and cycloaddition of anhydro-4-hydroxy-1,3-thiazolium hydroxides (thioisomünchnones), an approach to analogues of dehydrogliotoxin.
abstract: Dirhodium(II) tetraacetate catalysed reaction of the indoline diazo thioamide 8 gives the thioisomünchnone 9, a stable characterisable solid. This masked thiocarbonyl ylide undergoes 1,3-dipolar cycloaddition with N-methylmaleimide and maleic anhydride to give the exo-cycloadducts 10 and 11, characterised by X-ray crystallography. The thioisomünchnone 18, derived from diazo thioamide 17, is an extremely stable crystalline mesoionic system which can be characterised by X-ray crystallography but fails to undergo intramolecular cycloaddition. The related thioisomünchnone 19 can be generated by reaction of indoline-2-thione 7 with bromoacetyl chloride in the presence of triethylamine, and undergoes cycloaddition to give adducts 20 and 21.
authors.affiliation: School of Chemistry, University of Exeter, Stocker Road, Exeter, UK EX4 4QD. c.j.moody@ex.ac.uk
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Moody
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.forename: David
authors.initials: D
authors.lastname: Willows