Chemo, regio, and stereoselectivity in olefination of hydrazone 1,4-adducts between conjugated azoalkenes and sulphur co-activated methylene compounds

✍ Scribed by Orazio A Attanasi; Lucia De Crescentini; Paolino Filippone; Giuseppe Gatti; Fabio Mantellini; Stefania Santeusanio

• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 808 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(98)00392-5

✦ Synopsis

In the pre~nce ~ff ~xtium methoxide in catalytic amount, conjugated azoalkenes sm<x~thly add at rtx~m temperature (phenylsulphonyl)acetamide, methyl (phenylsulphonyl)acetate, methyl (phenylsulphinyl)acetate, (arylsulphonyl)acetonitriles, bis(phenylsulphonyl)methane. 'and (arylsulphonyl)nim~methane to yield the corresponding t~-functionalized hydrazonc derivatives by 1,4-'addition. In some cases the~ hydrazxmes were isolated, while in others their formation is accompanied by olefination products. Under the same reaction conditions and/or in methanol by means of gentle heating, ~veral of the~ adducts give rise to the related ~t,~-olefinated hydrazxme derivatives as pure isomeric lk)rms or as EF/EZ mixtures by loss of the nitro, sulphonyl or sulphinyl group. It is noteworthy that for l$-cyano-~arylsulphonyl adducts it was mainly detected the elimination of the arylsulphonyl group affording I~'yano-~x,Wolefinated hydrazones, while for analogous ~nitro-~arylsulphonyl adducts it was principally observed the loss of the nitro moiety producing 13,arylsulphtmyl-~,l~-olefinatedhydrazones-