ChemInform Abstract: Synthesis of N,N‐Disubstituted Lactone Hydrazones via (Sulfonylimino)‐Ethers.

Abstract

The dihydropyran 3 reacts with sulfonyl azides to give the known (sulfony1imino)-ethers ( = lactone sulfonylimines) 4 and 18. Reaction of 4 with NH2NH2. H,O leads to the aminotriazole-dibutanol 5, characterized as its tetraacetate 8, and not, as previously claimed, to 6 or 7. Similarly, the dihydrofuran-derived (tosy1imino)-ether 10 yields 11. The structure of 5 was established by X-ray analysis, and a mechanism for its formation is proposed. Carbanionic derivatives of N,N-dialkylated hydrazones are important intermediates for the regio-, diastereo-, and enantioselective formation of C,C bonds [ 1-41. Carbanionic derivatives of N,N-disubstituted lactone hydrazones of the type 1 and 2 (R',R* = alkyl, Scheme I ) , however, have so far not been used for C,C-bond formations, presumably because they are less easily available and less stable. The only method for the synthesis of N,N-disubstituted lactone hydrazones') is the one of Enders and coworkers [8] who cyclized N,N -dialkyl-o -chlorohydrazides by treatment with AgBF,.We wished to find new methods for the preparation of lactone N,N-dialkylhydrazones derived from valero-and from butyrolactone. These lactone hydrazones may be useful for the preparation of alkylated lactones; they are also models for 2-deoxyglycono-1 3 -and -1,4-lactone hydrazones. We are currently investigating the preparation and use of such glyconolactone hydrazones [9-1 I]. In this context, we noted a report by Huisgen and coworkers [I21 that the dihydropyran 3 reacts with tosyl azide (TsN,) to give the lactone tosylimine 4, and that 4 reacts with hydrazine hydrate (NH,NH,. H,O) in 75 % yield to a crystalline product to which Huisgen and coworkers assigned the structure 6 or 7, based upon an elemental analysis and an IR spectrum. Following their procedure, we obtained 4 and from the latter and NH,NH,. H,O a product (79%) with the same melting point and IR bands as the one reported (Scheme I ) . However, we observed that the reaction mixture developed a pink-to-red colour, and based on the spectral data of the I ) , )Taken from the Diploma Work of S. Fritschi, Zurich, 1989. Lactone imines react with 4-toluenesulfonohydrazides ( = tosylhydrazines) to yield lactone tosylhydrazones [5-71, but the analogous reaction with N,N-dialkylhydrazines did not lead to lactone N,N-dialkylhydrazones PI.