Addition to Oxygen-containing Multiple Bonds

Addition to Oxygen-containing Multiple Bonds. Addition to Nitrogen-containing Multiple Bonds.. . . ... 

Nitriles. Nitriles can be prepared by a number of methods, including ( /) the reaction of alkyl haHdes with alkaH metal cyanides, (2) addition of hydrogen cyanide to a carbon—carbon, carbon—oxygen, or carbon—nitrogen multiple bond, (2) reaction of hydrogen cyanide with a carboxyHc acid over a dehydration catalyst, and (4) ammoxidation of hydrocarbons containing an activated methyl group. For reviews on the preparation of nitriles see references 14 and 15. 

In all of these additions to various types of multiple bonds one notes that only products containing a sulfonyl group are obtained. There is never any indication of a bond being formed between a sulfinate oxygen and the species to which the addition is occurring. The same is apparently also true in the addition of a sulfinate ion to a sulfine (Veenstra and Zwanenburg, 1976). There addition occurs to the sulfur atom of the sulfine to form a sulfinyl sulfone ... 

The substituent R determines the reactivity of the isocyanate. Aromatic isocyanates react faster than aliphatic isocyanates, and carbonyl and sulfonyl isocyanates are considerably more reactive than the former. Isocyanate groups attached to oxygen or nitrogen are not stable in their monomeric forms. In cycloaddition reactions, isocyanates react preferentially across their C=N bonds, but additions across the C=0 bonds are also encountered. In this respect, isocyanates resemble ketenes (see Chapter 4, Section 4.1.). Suitable substrates for cycloaddition reactions are carbon multiple bonds (acetylenes, olefins, ketenes, etc.), C=N bond-containing compounds (imines, amidines, ketenimines, azines, carbodiimldes, etc.), C=0 bonds and C=S bond-containing substrates and phosphorus multiple-bond-containing substrates. Cycloaddition reactions of isocyanates across multiple metal bonds are also known. 

LOXs catalyse the addition of dioxygen to methyl-interrupted cis double bond [(Z,Z)-pentadiene] in a polyunsaturated fatty acid to produce a hydroperoxy fatty acid containing a Z,E conjugated double bond system. Where multiple pentadienes occur in a single molecule such as arachidonic acid, position-specific oxygenation can take place, resulting in the production of 5-, 12- or 15-hydroperoxyeicosa-tetraenoic acids. These hydroperoxy acids may be subsequently converted into other oxylipins by enzymic or non-enzymic reactions [3]. Table 1 shows some examples of LOX products from fungi. 

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