Ring opening oxidative

Tertiary alcohols are usually degraded unselectively by strong oxidants. Anhydrous chromium trioxide leads to oxidative ring opening of tertiary cycloalkanols (L.F. Fieser, 1948). 

Benzo[6]thiophene, 4,7-dialkoxy-synthesis, 4, 930 Benzo[6]thiophene, 2,3-dialkyl-synthesis, 4, 877-878 Benzo[6]thiophene, 3 -(dialkylamino)-synthesis, 4, 925 Benzo[c]thiophene, 1,3-diaryl-oxidative ring opening, 4, 768 Benzo[6]thiophene, 2,3-dibromo-reactions, 4, 830... 

Benzo[c]thiophene, 1,3-diphenyl-oxidative ring opening, 4, 768 synthesis, 4, 141-142... 

A similar oxidative ring opening is reported to take place when 7-methoxy-l-styryl-j8-carboline is oxidized. The product, which was reported to be identical with harminic acid, is presumably the related compound 283 (R = CO2H or H). 

An interesting oxidative ring-opening reaction is shown in Scheme 2.36. Oxidation of vinylaziridines 138 with m-CPBA gave 142 through [2,3] Meisenheimer... 

The whole process of chlorophyll disappearance in vascular plants is a complex multistep pathway, much as chlorophyll biosynthesis is, but for didactic reasons it can be abbreviated into two main stages. The first group of reactions produces greenish derivatives while the more advanced steps produce colorless compounds by an oxidative ring opening, analog to the oxygenolytic rupmre of the porphynoid macrocycle of haem. It is a very rapid process and despite considerable efforts, the detection of intermediates is difficult. ... 

Marusak RA, Mears CF. 1995. Exploration of selected pathways for metabolic oxidative ring opening of benzene based on estimates of molecular energetics In Valentine JS, Foote CS, Greenberg A, Liebman JE, editors. Active Oxygen in Biochemistry. New York Chapman and Hall. p. 336. 

Addition of alkyllithium to cyclobutanones and transmetallation with VO(OEt)Cl2 is considered to give a similar alkoxide intermediates, which are converted to either the y-chloroketones 239 or the olefinic ketone 240 depending on the substituent of cyclobutanones. Deprotonation of the cationic species, formed by further oxidation of the radical intermediate, leads to 240. The oxovanadium compound also induces tandem nucleophilic addition of silyl enol ethers and oxidative ring-opening transformation to produce 6-chloro-l,3-diketones and 2-tetrahydrofurylidene ketones. (Scheme 95)... 

Oxidative ring opening of isoxazolidines leads to nitrones. Thus, bicyclic isox-azolidines (50) and (51), treated with m-CPBA, afford nitrones (52), (53), (54), and (55) (Scheme 2.19). Conformational analysis has confirmed the key role of the nitrogen lone pair with respect to regioselectivity of the reaction and of the intramolecular kinetic deprotonation of the intermediate oxoammonium derivative (125). 

Similar oxidative ring opening occurs in other bi- and tricyclic isoxazolidines upon treatment with m-CPBA (126, 127). 

This strategy is a powerful route to bicyclic pyridones and their transformation products. Thus, these workers (40,41) applied this methodology to formal syntheses of the lupinine alkaloids ( )-lupinine and ( )-anagyrine (89) (Scheme 10.14). Imidosulfoxide (82) is converted to the corresponding isomiinchnone that is trapped with methyl acrylate to give 85. Oxidation, ring opening, and triflate formation... 

Whereas with quinoline the benzo ring is the more susceptible to oxidative ring opening, with isoquinoline the matter is more finely balanced. Use of ozone or alkaline permanganate results in attack on both the rings, the products being phthalic acid and pyridine-3,4-dicarboxylic acid (cinchomeronic acid) (38 Scheme 25). 

Oxidative Cleavage of Ketones. Aldehydes, and Alcohols Cycloalkanone oxidative ring opening... 

Methoxy-2-methyl-l,4-dihydro-4-oxoquinoline was converted into 6-methoxyisatin by an oxidative ring opening followed by ring closure.1150, Oxidation of 4-methyl-A-(2,3-dimethylphenyl)-carbostyril with alkaline permanganate gave A7-(2, li-dimethy lpheny 1) isatin.7 4... 

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