Subject using Group 111 halides

The use of halides as nucleophilic reagents is mostly covered by the chemistry of organometallic reagents that are readily formed from halides. This subject is covered by several volumes in the Chemistry of the Functional Groups series405"408 and elsewhere409"41. Thus this area of synthesis is not covered in the present work and the reader is directed to these sources for details. 

Nucleophilic-displacement reactions constitute some of the earliest known methods for the preparation of deoxyhalogeno sugars. A variety of leaving groups have been used, including sulfonyloxy (usually jP-tolylsulfonyloxy or methylsulfonyloxy), halide, triphenyl-methoxy (trityloxy), acetoxy, phosphate, and nitrate. As Barnett has surveyed the reactions in Volume 22 of this Series,1 this subject will not be discussed comprehensively in the present Chapter instead, only some general comments will mainly be made that will also be relevant to later discussions. 

The SRN1 subject has already been reviewed [4,107, 108,109,110, 111] and the large variety of the used anions (carbanions, nitronates, thiolates, enolates, anions of group V etc... ) with several electron accepting substrates (chloron-itro- or dinitro- compounds, dimethylsulfoxide, organic halides, etc.. . ) was... 

The Michaelis-Arbuzov reaction is the most used and well-known method for the synthesis of phosphonates and their derivatives and may also be used to synthesize phosphinates and tertiary phosphine oxides. The simplest form of the Michaelis-Arbuzov reaction is the reaction of a trialkyl phosphite, 3, with an alkyl halide, 4, to yield a dialkyl alkylphosphonate, 6, and new alkyl halide, 7 (Scheme 2). During this transformation the phosphorus atom of a ter-valent phosphorus(III) species (3) acts as a nucleophile resulting in the formation of an intermediate alkoxy phosphonium salt 5, containing a new [P—C] bond. The precise structure of the intermediates 5 is a subject of debate—as reflected by common reference to them as pseudophosphonium salts —with a penta-coordinate species (containing a [P—X] bond) being proposed and detected in some cases.18 Decomposition (usually rapid under the reaction conditions) of the intermediate 5 by nucleophilic attack of X- on one of the alkyl groups R1, with concomitant formation of a [1 =0] bond yields the product pentavalent phosphorus(V) compound (6) and the new alkyl halide, 7. 

Ben2 yl-type chlorides are converted to the corresponding cyanides much more rapidly (85-90%). Ring substituents include alkyl, halo, carbethoxy and nitro groups. The more reactive benzyl halides, particularly the p-methoxy derivatives, are subject to extensive alcoholysis when ethanol is employed as the solvent. The successful use of acetone, acetonitrile, and phenylacetonitrile as solvents has been described. Conversion by cuprous cyanide and pyridine has been successfully applied to benzyl chloride as well as to di-o-tolylchloro-methane. It is interesting to find that treatment of a-chloroethylbenzene, C,H,CH(C1)CH, with cuprous cyanide gives 1,3-diphenyI-l-butene,... 

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