Uwe Schön

Unanticipated formation of ortho-sulfone substituted phenols by anionic thia-Fries rearrangement of (aryl triflate)tricarbonylchromium complexes

Tricarbonylchromium complexes of aryl triflates undergo base-mediated anionic thia-Fries rearrangements to generate push-pull substituted [ortho-hydroxyaryl(trifluoromethylsulfonyl)phenol]tricarbonylchromium complexes under very mild reaction conditions.

A new reagent and its polymer-supported variant for the amidination of amines

Abstract New reagents for the high yielding amidination of primary and secondary amines are described. By attaching a benzyl substituent to the 3,5-dimethyl-1 H -pyrazole-1-carboxamidine ring, a reagent 1 is obtained which allows easy work-up after amidination because of solubility of byproducts in organic solvents. In addition, the polystyrene-bound analogue 2 was prepared which allows amidination of various amines with high purity.

The stereochemistry of spiropiperidine cyclizations (histrionicotoxin, part I)☆

Abstract The spirocyclization of straingt-chain triketo-intermediates, similar to possible biogenetic precursors of histrionicotoxin, is shown to be stereoselective, generating the non-natural configuration at C-2. Aiming at an sp2-center in this position, triketo-brassylic ester was treated with ammonia at room temperature and was shown to cleanly and efficiently yield a spiroketone.