Alkyl hypohalites

This alkoxyfluorination leads to alkoxy fluoro and difluoro compounds. The product distribution depends on the reaction conditions. Similarly, fluoro halides are obtained in addition to alkoxy halides using a combination of boron trifluoride and alkyl hypohalite.50... 

Other alkyl hypohalites usually add to carbon-carbon multiple bonds in a free-radical process.155-158 Ionic additions may be promoted by oxygen, BF3, or B(OMe)3.156-160 While the BF3-catalyzed reaction of alkyl hypochlorites and hypo-bromites gives mainly halofluorides,159 haloethers are formed in good yields but nonstereoselectively under other ionic conditions.156-158 160 In contrast, tert-BuOI reacts with alkenes in the presence of a catalytic amount of BF3 to produce 2-iodoethers.161 Since the addition is stereoselective, this suggests the participation of a symmetric iodonium ion intermediate without the involvement of carbocationic intermediates. 

The photolysis of alkyl hypohalites, especially alkyl hypoiodites [29], can be used in a manner similar to the organic nitrites for functionalization of an unactivated carbon atom. Scheme 25 outlines a general scheme for remote functionalization by the hypoiodite reaction. Readers requiring more information on this subject are advised to refer to review articles [2c, 16, 20],... 

The latter possibility obeys the peculiar synergistic effect of the C-2 alkoxy substituent of I that makes these dihydropyrans unique. Without it, nothing of this occurs. These substrates have been used for the detection of positive charge development at C-6, among other things, in additions of alkyl hypohalites and some diazocarbonyl compounds to the double bond, and in the interesting fragmentation of norcarane derivatives illustrated in Scheme 38.2. ... 

Suginome, H., Reaction and Synthetic Application of Oxygen centered Radicals Photochemically Generated from Alkyl Hypohalites. In Horspool, W. M., Lenci, F. (eds), CRC Handbook of Organic Photochemistry and Photobiology, 2nd edn, CRC Press LLC, Boca Raton, FL, 2004, Chapter 109, pp. 1 16. 

Hypohalites s. Acetyl hypo-bromite, Alkyl hypohalites, Hypochlorites, Potassium hypobromite. Sodium hypochlorite... 

As anticipated, the W-halosuccinimides (50) and alkyl hypohalites are reactive toward trivalent phosphorus compounds. The biphilic mechanism for hypohalite decomposition has been clarified using optically active phosphines (51,52). 

The mechanism by which hypohalites oxidize alcohols probably involves initial formation of an alkyl hypohalite (Eq. 16.16). This product arises from reaction of the alcohol with the hypohalous acid that is in equilibrium with hypohalite ion in aqueous medium (Eq. 16.15). Base-promoted E2 elimination of the elements of H-X from the alkyl hypochlorite leads directly to either an aldehyde or ketone. The advantage of using hypohalite as an oxidant is immediately obvious upon examining Equation 16.16. The inorganic by-product derived from the oxidant is a halide salt that can be safely flushed down the drain. Reactions that do not produce toxic by-products are environmentally friendly and are now commonly referred to as "Green Chemistry." (See the Historical Highlight at the end of this chapter.)... 

Alkyl hypohalites (ROX X = Cl, Br, 1), a class of molecules that can be prepared from the corresponding alcohols by a variety of methods, dissociate to alkoxyl and halogen radicals with high efficiency upon irradiation with light of wavelength longer than 300 nm (Scheme 1). 

Methyl and ethyl hypochlorites, the first alkyl hypohalites known, were prepared by Sandmeyer in 1885. Chattaway and Backeberg of Oxford subsequently reported the preparation of alkyl hypochlorites such as propyl, isopropyl, and f-butyl hypochlorites in 1923 and observed that although the primary and secondary hypochlorites are very unstable and decompose rapidly at room temperature, the tertiary hypochlorites, such as f-butyl hypochlorite, prepared by the reaction of chlorine, sodium hydroxide, and... 

Since this early work, studies from the late 1950s until the 1960s by Walling, Green, Kochi and their collaborators using t-alkyl hypohalites disclosed some fundamental characteristics of the principal radical chain reactions, such as intermolecular hydrogen abstraction and P-scission of intermediate alkoxyl radicals in hypohalite photolysis. This work was summarized in a review article by Kochi."... 

Alkyl hypochlorites, as prototype alkyl hypohalites, in carbon tetrachloride exhibit two absorption peaks in the ultraviolet region one at about 260 nm and the other at about 310-320 nm. " Specifically, 3 3-acetoxy-20-methylallopregnan-20-ol hypochlorite in carbon tetrachloride exhibits two absorption maxima... 

Homolysis is also initiated by azoisobutyronitrile or by thermolysis. This characteristic of alkyl hypohalites differs from those of the corresponding nitrites in solution homolysis of the ON bond in solution can only be achieved by photolysis. 

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