And ozonolysis

A 20) oiefin Formation via Enol Acetates and Ozonolysis A stock solution of acetylating mixture is prepared by dissolving 0.2 ml of 70-72% perchloric acid in 5 ml of acetic anhydride. To a solution of 5 g of 3a,6a-diacetoxy-5jff-pregnan-20-one in 50 ml of carbon tetrachloride is added 5 ml of the above stock perchloric acid-acetic anhydride solution and the mixture is allowed to stand at room temperature for 1.25 hr. The mixture is... 

The synthesis was carried out by the Diels-Alder addition and ozonolysis with reductive work-up. No... 

In his first independent work, Helferich prepared y-hydroxyvaleral-dehyde (4-hydroxypentanal) by reduction and ozonolysis of methylhep-tenone, readily available from citral by a retro-aldol reaction. He was able to show that, similarly to the saccharides, this hydroxyaldehyde exists in... 

Fig. 4 TOC removal with y-Al203 and y-AljOj supported catalysts during catalytic ozonolysis and ozonolysis followed by adsorption.

Weavers LK, Ling FH, Hoffmann MR (1998) Aromatic compound degradation in water using a combination of sonolysis and ozonolysis. Environ Sci Tech 32 2727-2733... 

Diastereoselective conjugate addition of oxygen and nitrogen- centered nucleophiles to nitroalke-nes derived from (+)-camphoisulfonic acid and ozonolysis give a-hydroxy and a-amino thiol acid derivatives (Eq. 4.39). In all cases, the (/ )-diasteromer is formed as the major component.49... 

The use of both ozonation and ozonolysis is reviewed32. Ozonation leads to ozonide and ozonolysis leads to oxidized fragments, showing the use of both oxidative (AgN03) or reductive [(CH3)2S or PI13P] methods to produce the FAME (fatty acids methyl esters) that by subsequent GC analysis enabled determination of the position of the double bonds in the original molecule (equations 2-4). 

The much larger rates of heat transfer in microreactors allow highly exothermic reactions that are difficult to control in conventional batch systems, such as direct fluorination (Chambers and Spink 1999 Jah-nisch et al. 2000 de Mas et al. 2003) and ozonolysis (Wada et al. 2006). Thus, microreactors expand the number of possible reactions and feasi-... 

Wada Y, Schmidt MA, Jensen KF (2006) Flow distribution and ozonolysis in gas-liquid multichannel microreactors. Ind Eng Chem Res 45 8036-8042... 

Hydrolysis of 20 with the aid of butanol followed by syn-selective reduction of jS-keto ester 21 and protection as the isopropylidene acetal was accomplished in 87% yield. L1A1H4 reduction and TBS protection of the primary alcohol gave 22 in very good yields. In this strategy, the furan residue serves as an aldehyde synthon and ozonolysis followed by esterification gave the corresponding methyl ester. Reduction and consecutive oxidation established aldehyde 23 in 71% yield. 

Grimsrud, E. P., H. H. Westberg, and R. A. Rasmussen. Atmospheric reactivity of monoterpene hydrocarbons, NOs photooxidation and ozonolysis. Int. J. Chem. Kinet. Symp. 1 (Chemical Kinetics Data for the Lower and Upper Atmosphere) 183-195, 1975. 

TABLE 3-14 Photoxidation and Ozonolysis Rates of Monoterpene Hydrocarbons"... 

Christi, M., and G. Bruentrup. 1974. Diimine reduction and ozonolysis of benzva-lene. Chemische Berichte 107 3908-14. 

Thus, allylmagnesium bromide affords from 25 and 26 the 4.5-threo adducts 27 and 28 in 95 5 ratio with the A.5-erYthro materials 29 and 30. The latter products, formed according to Felkin s model, are obtained in 7 3 ratio with 27 and 28 when diallylzinc is added to 25 and 26. The set 27—30, as before, on N-protection and ozonolysis, affords L-vancosamine 34 and its configurational isomers 31—33. 

Furthermore, yeast treatment of the a-acetoxy ketone 53, bearing two oxygen substituents ( ) at a and affords the carbinol 54 in 20 % yield, somewhat less than 10 % of the (2R) diastereoisomer, and 70 % of recovered starting material. From the carbinol 54, crystalline 55 is obtained, which may be converted through suitable manipulation of the protecting groups and ozonolysis, into A-deoxy-D-talo-hexose 56. The minor diastereoisomer similarly affords A-deoxy-D-xylo-hexose 57. Thus, in the yeast treatment of 53, as the results of the enzymic kinetic resolution, the (2S, 4S, 5R) diol 55, a carbohydrate-like chiral synthon, is accessible out of eight possible isomers. 

Ozonolysis of the O-methyl oximes of cyclic ketones in the presence of 1,4-cyclohex-anedione and ozonolysis of the O-methylated dioxime of 1,4-cyclohexanedione in the presence of cyclic ketones afforded the corresponding diozonides . 

Major efforts to determine the structures of the optically active alkaloids were made with cryptaustoline iodide, and preliminary examination showed that the molecular formula could be expressed as CjgHjj(OH)(OCH3)3(NCH3)" I . Products obtained after Hofmann degradation and ozonolysis were identical with compounds obtained earlier by Robinson and Schopf from racemic 14, and the structure as one of the optical isomers of O-methylcryptaustoline iodide was established. 

The structure of cryptowoline iodide (2) was determined by a similar set of reactions. Both O-methyl and 0-ethyl ethers were subjected to exhaustive meth-ylation, elimination, reduction, and ozonolysis. The key compounds obtained from the ethyl ether were 26 and 6-aminopiperonal. The amine fragment showed the methylenedioxy group to be at the 9,10 position in cryptowoline, and the fact that the same aldehyde 26 was obtained from 0-ethylcryptowoline iodide fixed the position of the free OH as in cryptaustoline to C-2. 

Finally, a series of novel hydroperoxy-l,2-dioxanes 233a, b (Scheme 65) were synthesized by hydroperoxide rearrangement and ozonolysis <2006EJ02174> all the products showed weak antimalarial acitivity. Also the epoxy-endoperoxides 234a,b were designed which proved to have inhibitory acitivity against Candida albicans (Scheme 65) <2007BMC36>. 

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