1- Acetoxy-2,4-hexadiene

So kann z.B. 6-Chlor-3-nitro-2,3,4-trimethyl- bzw. 6-Acetoxy-3-methyl-3-nitro-l,4-cyclo-hexadien mit einer waBrigen Losung aus Natriumnitrit und Tetrabutylammoniumbromid in Dichlormethan bei 0° in 6 h in 60%iger Ausbeute zu 5-Nitro-1,2,3-trimethyl-benzol bzw. 4-Methyl- 1-nitro-henzol rearomatisiert werden2 ... 

Diels-Alder reactions. Although 2,4-hexadiene shows only slight regioselec-tivity in Diels-Alder reactions, the 1-acetoxy derivative (1) undergoes regioselective cycloaddition with a variety of dienophiles.1... 

Oxidative cyclization of 1,5-hexadienes.3 Palladium(II)-catalyzed oxidation of these substrates with p-benzoquinone (0.2 equiv.) and Mn02 (1 equiv.) (c/. 12, 367) results in cyclization to acetoxy-substituted methylenecyclopentanes as the major product. 

Grignard reagents, 138 Methyl acrylate, 183 Palladium catalysts, 230 Ruthenium(III) chloride, 268 Other methods l-Acetoxy-2,4-hexadiene, 2 Palladium catalysts, 230 Tri-p-carbonylhexacarbonyldiiron, 320... 

Another type of oxycarborative addition is achieved when the organopalladium intermediate is trapped via alkene insertion. Thus, 1,5-hexadiene with acetic acid gives l-acetoxy-3-methylenecyclopentane (3) if mediated by palladium(ll) acetate10. This reaction is obviously restricted to 1,5-dienes, since other nonconjugated dienes and even some substituted 1,5-dienes lead to linear oxidation products. 

The Pd-catalyzed elimination is extended to the synthesis of conjugated trienes and tetraenes. Reaction of ( , )-hexadienyl acetate gave (Ej-hexatriene exclusively (>EIZ = 97 3) in 87% yield. On the contrary an 80 20 mixture of isomeric E- and Z-hexatrienes was formed in 67% yield in the reaction of 3-acetoxy-l,5-hexadiene. ( , )-l,3,5,7-Octatriene was also prepared from ( , , )-2,4,6-octatrienyl acetate (Scheme 7). 

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