Rearrangements tosyl hydrazones

A 2-cyclohexenone derivative can be transformed into the corresponding epoxy tosyl-hydrazone by sequential treatment with peracid and tosylhydrazine. The elimination of nitrogen and p-toluenesulfinate and fragmentation after rearrangement to the 3-tosylazo allylic alcohol may occur under mild conditions. Carbonyl compounds with 5,6-triple bonds are formed in high yields (J. Schreiber, 1967 M. Tanabe, 1967). If one applies this reaction to a 9,10-epoxy-1-decalone, a ten-membered 5-cyclodecyn-l-one ring is formed (D. Felix, 1971). This product is an important intermediate in the perfume industry and has been used on a large scale. For this purpose Eschenmoser developed a synthesis in which the readily removed styrene was split off instead of a sulfmic acid. Thus a l-amino-2-phenylaziridine hydrazone was used instead of a tosylhydrazone (D. Felix, 1968). ... 

The protic reaction on occasion is a useful method of alkene formation, but is far from general because the cation intermediate tends to undergo rearrangements.Further, even for cases in which elimination to an alkene is the predominant pathway, the regioselectivity of the process is often mediocre. A key step in the synthesis of (+)-a-eudesmol and (-)-a-selinene exemplifies this point (Scheme 60). There are, however, isolated examples of excellent selectivity, such as the reaction of a 3-ketotetrahydrofuran tosyl-hydrazone salt to give the corresponding cyclic enol ether as the major product (Scheme 61), the intro-... 

Vol. 8, p. 40) work to synthesize the benzofuranone (139) and related compounds by acid ion-exchange resin rearrangement of the corresponding aldehydoacetate." Last year s Report omitted mention of the routine synthesis of (8i )-(- -)- and (85)-(+)-[9- Hi]-a-terpineol via epoxide reduction (Vol. 8, p. 42, ref. 371) and syntheses of some deuteriated pulegones and pulegone tosyl-hydrazones. ... 

The relative amount of base has a significant effect on the product distribution. When the tosyl hydrazone of pinacolone was treated with > 1.8 equivalents of n-butyllithium, 3,3-dimethyl-l-butene was formed. When only 1 equivalent of n-butyllithium was used, however, a 57% yield of 3,3-dimethyl-l-butene, 40% of 1,1,2-trimethylcyclopropane, and 3% of the rearranged alkene (2,3-dimethyl-1-butene) were isolated.264 jhe type of base employed is also important. The product distribution from the hydrazone of cyclopentanone, for example, gave a mixture of cyclopentene/( )-2-pentene/(Z)-2-pentene.265 When sodium methoxide was used, a 2 84 14 mixture of these products was obtained whereas sodium hydride led to a 83 14 3 mixture and sodium amide a 60 35 3 mixture.265... 

Rearrangement of a norbornane system into a pinane one which, as already noted, rarely occurs in solvolysis, does take place in the photolysis of tosyl-hydrazones in aqueous NaOH or CHjOH/CHjONa... 

The Neber rearrangement involves the base-catalyzed conversion of oxime tosylates, quaternary salts of hydrazones or /V-chloroimines to a-amino ketones via isolable azirine intermediates (equation... 

Benzenesulfonamide, Ar,AT-dibromo-4-methyl-(TsNBr2) bromohydrination with, 287 Benzenesulfonamides reductive cleavage, 247 synthesis of drugs, 301, 307-308 Benzenesulfonic acids. See Sulfonic acids Benzenesulfonic acid, 4-methyl-, esters (tosylates) alkyl a-synthons, 16, 24, 47, 93 fragmentation of, 89 rearrangement of, 32 reductive cleavage of, 114, 202-203 —, 4-methyl-, hydrazide (tosylhydrazine) hydrazones of fragmentation, 89 reduction, 109... 

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