Acyl oxidation

This section deals first with the preparation of alkyl acyl oxide compounds—esters—by the interaction of an acid or an acid derivative and an alcohol. The fact that the formation of an ester and water from a mixture of an acid and an alcohol is a reversible reaction necessitates special measures being adopted to displace the equilibrium towards the more complete formation of ester. 

The second portion of the section discusses the preparation of di-acyl oxide compounds—acid anhydrides. 

The formation of a sol-gel porous material is through a hydrolysis-polycondensation reaction. An example is given in equation 1 with the methoxide of silicon (tetramethyl-orthosilicate, TMOS), but many other alkoxides, aryl oxides and acyl oxides can be used, as well as Si—N and Si—Cl compounds. 

M. Kunz, J. Kowalczyk, and S. Ehrhardt, Use of acylated oxidized carbohydrates as bleach activators and sequestrants in detergent formulations, Eur. Pat. Appl. EP 731161 (1996) Chem. Abstr. 125 (1996) 279255. 

Aminopenici11 anic acid (I) is acylated, oxidized and esterified to give the sulfoxide ester (II). Sulfoxide ester (II) is converted to its C-6 epimer (III) by treatment with trimethyl chiorosilane and triethyl amine. Rearrangement of III using triphenyl phosphine yields the epioxazoline (IV). 

The azocane nitrogen undergoes reactions characteristic for secondary amines nucleophilic substitutions (alkylations and acylations), oxidations, and modifications to ring substituents. Alkylations. Halo derivatives were reported to react readily with azocanes to afford in good yields compounds with diverse applications in life sciences (Scheme 101 <1997JME1578 . 

A larger 600-member bergenin-based library using acylations, oxidations, halo-genations, and glycosylations and a 24-member 3,6-dihydroxytropane library have been prepared by the same group (313) a library of acylated taxol derivatives was also reported (314). A survey of theoretical applications for combinatorial biocatalysis has recently appeared (315). 

The route is based upon an acylation-oxidation-deacylation sequence, with commercially available, inexpensive 1,3-dithiane employed as the starting material. 2-Acyl-1,3-dithianes have proved to be particularly effective substrates for asymmetric oxidation in our hands,7,9,11,12 and as 2-(2,2-dimethylpropanoyl)-1,3-dithiane undergoes this asymmetric oxidation most efficiently (ca. 90% ee), it was chosen as the intermediate. 

In a specific work, it has been shown that chemical modification of hyperforin by acylation, oxidation and alkylation produce detrimental effects on the molecule activity as inhibitor of serotonin uptake [89], and the presence of the enolized cyclohexanedione moiety in its structure has been related to its efficacy on the re-uptake of neurotransmitters. 

Brown s conditions afforded 564 with high ee. Acylation, oxidative cleavage of double bond, and Wittig olefination gave (Z)-vinyl iodide 565. 

The reactions of alicyclic olefins with Se02 have been extensively investigated. Heating cyclopentene with Se02 in acetic anhydride (acylating oxidation) oxidizes it to much monoacetoxy- and a little diacetoxy-cyclopentene but in a bomb tube at 90-100° much diacetate and little monoacetate are obtained.225 Thus the second methylene group next to the double bond is more or less attacked according to the reaction conditions. 

A complication arises from the functionalities of the biological macromolecules typically involved in ligand-protein interactions certain structural features of the ligand determine whether a compound is a substrate (having a functional group which is hydrolyzed, acylated, oxidized, etc., by an enzyme),... 

Moreover, the La modified zeolites were also used to catlytic alkylation, acylation, oxidation, acetoxylation, hydration and non-oxidative aromatization, etc. Please see the relative reports if you are interested in these catalytic fields [164-176]. 

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