Functional desymmetrization of 1,3-dioximes for the obtention of 1,2,3-hetero trisubstituted carbocycles

Abstract

Carbocylic 1,3-dioximes react with acyl chlorides giving systems that may, upon heating, suffer [3,3]-sigmatropic rearrangements in high yields in only one of the oximes esters, yielding 1,3-dinitrogen-2-oxygen trisubstituted carbocycles. Use of more reactive electrophiles, such as p-toluenesulfonyl chloride and diethyl chlorophosphate, introduces the halogen at position 2, while cleaving the N–O bond of just one of the oxime functions. 2010 Elsevier Ltd. All rights reserved. 1,2,3-Hetero trisubstituted carbocycles are important structural features found in a variety of products of practical importance. Examples are manifold and can bear the 1,2,3-trihydroxy motif, as in the key biosynthetic precursor shikimic acid, or include other heteroatoms, such as nitrogen, as in the 1,2-diamino-3-hydroxy present in the anti-flu drug Tamiflu . 1 The size of the cycle can also vary, and the 1,2,3-trisubstituted motif can be found embedded in, for example, 5-membered rings, part of more complex structures. 2,3 We disclose in this work a method to generate precursors of the densely functionalized system of 1,3-diamino-2-hydroxy carbocycles by functional desymmetrization of simple symmetrical cyclic 1,3-dioximes 1 (Scheme 1). These are simple compounds which can be easily generated from the corresponding 1,3-dicarbonyl compounds by reaction with hydroxylamine. 4 In basic