1,3-dioxolane, oxidation

Norbomanone 3 has been first transformed into the chetal 4 by Swem oxidation and selective transacetalization with 2-methyl-2-ethyl-dioxolane. Oxidation with m-... 

The oxidation of terminal alkenes with an EWG in alcohols or ethylene glycol affords acetals of aldehydes chemoselectively. Acrylonitrile is converted into l,3-dioxolan-2-ylacetonitrile (69) in ethylene glycol and to 3,3-dimetho.xy-propionitrile (70) in methanol[28j. 3,3-Dimethoxypropionitrile (70) is produced commercially in MeOH from acrylonitrile by use of methyl nitrite (71) as a unique leoxidant of Pd(0). Methyl nitrite (71) is regenerated by the oxidation of NO with oxygen in MeOH. Methyl nitrite is a gas, which can be separated easily from water formed in the oxidation[3]. 

Perfluoroepoxides have also been prepared by anodic oxidation of fluoroalkenes (39), the low temperature oxidation of fluoroalkenes with potassium permanganate (40), by addition of difluorocarbene to perfluoroacetyl fluoride (41) or hexafluoroacetone (42), epoxidation of fluoroalkenes with oxygen difluoride (43) or peracids (44), the photolysis of substituted l,3-dioxolan-4-ones (45), and the thermal rearrangement of perfluorodioxoles (46). 

Mesityl oxide and hydrogen peroxide react initially to form the cycHc hydroxyalkyl alkyl peroxide, a 1,2-dioxolane. Prolonged equiUbration results in formation of the cycHc di(alkylperoxyalkyl) peroxide, 3,3 -dioxybis(3,5,5-trimethyl-l,2-dioxolane) [4507-98-6] (122,138) ... 

Carbonyl Compounds. Cychc ketals and acetals (dioxolanes) are produced from reaction of propylene oxide with ketones and aldehydes, respectively. Suitable catalysts iaclude stannic chloride, quaternary ammonium salts, glycol sulphites, and molybdenum acetyl acetonate or naphthenate (89—91). Lactones come from Ph4Sbl-cataly2ed reaction with ketenes (92). 

The kinetics of formation and hydrolysis of /-C H OCl have been investigated (262). The chemistry of alkyl hypochlorites, /-C H OCl in particular, has been extensively explored (247). /-Butyl hypochlorite reacts with a variety of olefins via a photoinduced radical chain process to give good yields of aUyflc chlorides (263). Steroid alcohols can be oxidized and chlorinated with /-C H OCl to give good yields of ketosteroids and chlorosteroids (264) (see Steroids). /-Butyl hypochlorite is a more satisfactory reagent than HOCl for /V-chlorination of amines (265). Sulfides are oxidized in excellent yields to sulfoxides without concomitant formation of sulfones (266). 2-Amino-1, 4-quinones are rapidly chlorinated at room temperature chlorination occurs specifically at the position adjacent to the amino group (267). Anhydropenicillin is converted almost quantitatively to its 6-methoxy derivative by /-C H OCl in methanol (268). Reaction of unsaturated hydroperoxides with /-C H OCl provides monocyclic and bicycHc chloroalkyl 1,2-dioxolanes. 

Ethylene carbonate (l,3-dioxolan-2-one) is commercially prepared from ethylene oxide by the addition of carbon dioxide to ethylene oxide with either ammonium or alkaU metal salts as catalysts (87) ... 

Dioxolanes can be cleaved by acid-catalyzed exchange dioxolanation, acid-catalyzed hydrolysis, or oxidation. Some representative examples are shown below. I... 

Perchloric acid (79% HCIO4/CH2CI2, 0°, 1 h 25°, 3 h, 87% yield) and periodic acid (aq. dioxane, 3 h, quant, yield) cleave 1,3-dioxolanes the latter drives the reaction to completion by oxidation of the ethylene glycol that forms. Yields are substantially higher from cleavage with perchloric acid (3 AHCIO4/THF, 25°, 3 h, 80% yield) than with hydrochloric acid (HCl/HOAc, 65% yield)... 

By copolymerising with a small amount of second monomer which acts as an obstruction to the unzipping reaction, in the event of this being allowed to start. On the industrial scale methyl methacrylate is sometimes copolymerised with a small amount of ethyl acrylate, and formaldehyde copolymerised with ethylene oxide or 1,3-dioxolane for this very reason. 

It is stated in the basic patent that ethylene oxide (II) and 1.3-dioxolane (III) are the preferred materials. By the occasional incorporation of molecules containing two successive methylene groups the tendency of the molecules to unzip is markedly reduced. 

Accordingly, the cyclopropenylidene anthrones 190/198 were converted by ferric chloride in hydroxylic solvents to the allene ketal 466, whose hydrolysis gives the allenic ketone 46 7288. The dioxolane 468 was obtained from the alkyl-substituted quinocyclopropene 190 in glycol and the ketone 467 in methanol. Apparently FeCl3 served not only as an oxidant, but also as a Lewis acid assisting solvent addition to C1 2 of the triafulvene. 

Dioxolanes 39 derived from a, 3-unsaturated aldehydes react with nitrile oxides R2CNO to give the corresponding isoxazolines 40 with the 1,3-dioxolan-2-yl substituent in position 4 as main products, and their 5-isomers as minor products with good regioselectivity and synthetically useful yields. The corresponding... 

Cyclic acetals. In combination with iodine, this reagent resembles lead tetraacetate in the ability to generate alkoxy or aminyl radicals (12,243) under thermal or light activation. This radical oxidation can be used to convert p- or y-hydroxy ethers into dioxolanes or dioxanes.4... 

Upon chemical oxidation, the AT-(5-methyl-2-oxo-l,3-dioxol-4-yl)meth-yl derivative of norfloxacin (8.65, R = H, R = 8.191 with R" =Me) discussed above yielded an oxodioxolane derivative, i.e., /V-[(4-mclhyl-5-meth-ylidene-2-oxo-l,3-dioxolan-4-yl)oxy]norfloxacin (8.65, R = H, R = 8.192) [252], This compound had modest activity in vitro as an antibacterial agent. 

A-Hydroxyphthalimide (88) has also been shown to be an effective mediator for the oxidation of alcohols [120]. The oxidation process depicted in Scheme 32 is suitable for the oxidation of secondary alcohols (86). A-Hydroxyphthalimide also plays an important role as a mediator for deprotection of the 4-phenyl-l,3-dioxolane... 

The oxidation of dihetarylethene 44 with m-chloroper-benzoic acid (m-CPBA) in CH2CI2 afforded 1,1-dioxide 67 (06T5855, 073173, 08CC4622, 09JMC97) in yields up to 90% in the case of the 6-acetyl derivative, the yield of bis-sulfone 68 was only 35% (06T5855) because of a Baeyer-ViUiger oxidation side reaction of the carbonyl group. Protection of the latter as the dioxolane derivative made it possible to increase the yield of 69 to 72% (Scheme 21). 

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