1,3-dienes oxidation

Cyclopentene, cyclohexene, and cycloheptene were obtained by intramolecular oxidative couplings of the bis-ylides (161 n = 3, 4, or 5) but oxidation of (161 n = 2) gave cyclo-octa-1,5-diene. Oxidation of the bis-ylide (161 n — 8) gave cyclic polyenes containing 20, 30, 40, 50, and 60 atoms. 

Some of the earliest work in the oxidation of alkenes was performed by oxidation with potassium permanganate. Under acidic and neutral conditions the intermediately formed glycols are oxidized, generally leading to cleavage of the carbon-carbon bond. Thus, such procedures have seldom been synthetically applied to diene oxidation. One notable... 

P/A/)-5,6,7,8-Tetrahydrodibenzo ,c)cycloocta-l,3-dienes Oxidative Aryl Coupling with Thallium(lll) Oxidants General Procedures13 ... 

Duescher, R.J. Elfarra, A.A. (1994) Human liver microsomes are efficient catalysts of 1,3-buta-diene oxidation evidence for major roles by cytochromes P450 2A6 and 2EI. Arch. Biochem. Biophys., 311, 342-349... 

A mild triple catalytic system consisting of Pd(OAc)2, hydroquinone, and a transition metal macrocycle (for example, iron phthalocyanine) was reported [243]. The catalytic effect is carried out by the interaction of Pd(II) with the substrate and the acquisition of two electrons, which are further transferred to the benzoquinone that is reduced to hydroquinone. The hydroquinone is then reorganized to benzoquinone by the 02/metal macrocycle system. The following types of transformations were carried out in mild conditions using the developed system 1,4-oxidation of conjugated dienes, oxidation of terminal olefins to methyl ketones, and allylic oxidation. 

Oxidation of 1,4-dienes. Oxidation of the 1,4-diene 1 with PCC in CH2CI2 affords dienones 2 and 3 in the ratio of 9 1 (70% total yield). Complementary rcgioselectivity (2/3 = 1 3) is achieved with CrOj-2Py or terf-butyl chromate as the... 

Diene Oxidant (equiv)3 Solvent Temp fC) Time Yield (%) mp rc) Ref... 

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