Arbuzov-type rearrangements

Reactions involving alkoxy- or aryloxyphosphines with amines might also be expected to yield phosphazane oligomers/polymers. However, PhP(0Ph)2 with 1,2-(NH2)2c6Hit produced only the Arbuzov type rearrangement product CgHi, (NH) 2P(0)Ph. 

Similarly, the reaction between sulfur tetrafluoride and tris(dimethylamino)phosphane proceeds with oxidation of the phosphane in addition to fluorine transfer to give tris(dimethylamino)-difluoro-A5-phosphane (18) as the main product. In contrast, the reaction with tris(methyl-sulfanyl)phosphane does not give a straightforward fluorination extensive Arbuzov-type rearrangements and fluorination reactions occur.220... 

Several promising processes are applied to the synthesis of 2-cyanoethylphosphonates, including, for example, the thermally induced Michaelis-Arbuzov-type rearrangement of diethyl 2-cyanoal-lylphosphite to diethyl 2-cyanoallylphosphonate (Scheme 6.30).- " -4 ... 

Exposure of 253 (R = Pr ) to ultraviolet radiation leads to an unusual Arbuzov-type rearrangement to yield 276. This photochemical dealkylation reaction results in a bridging phosphonate and a new hydride ligand located on the... 

Pummerer rearrangements leading to thiolesters are discussed in the later sections on sulphoxides. A superficially related Arbuzov-type reaction, with a 1,2-shift of sulphur, through the intermediate (5), has a similar outcome. 2-Thiopyridyl chloroformate has been advocated as a reagent for the conversion of carboxylic acids into their pyridine-2-thiolesters under mild conditions. 

The first compound of this type that was obtained was the cobalt complex [CpCo[P(OR)20]3]2Co + (56) (Scheme 37) of Co . It is formed when cobaltocene is treated with P(OR)3 at about 120 °C in a reaction that comprises substitution of a Cp by P(0R)3 followed by a triple Arbuzov rearrangement (see Arbuzov Rearrangement) and complexation of the cobalt ion liberated during the reaction. When (56) is treated with cyanide, the central cobalt ion is extracted as Co(CN)e, thereby liberating the free ligand (55) (Scheme 37). Remarkably, the very inert cobalt atom incorporated in the... 

In 1952 Perkow discovered a new type of rearrangement in which trialkyl phosphites react with a-aldehyde.6,7 This anomalous Arbuzov reaction, which resulted in the formation of dialkylvinylphosphates, subsequently became known as the Perkow reaction. 1 The reaction of trialkyl phosphites with alkyl halides (Arbuzov reaction) proceeded to yield dialkoxy alkyl phosphonates.8 The alkyl halide undergoes a nucleophilic displacement to yield the nonisolable alkyl trialkoxy phophonium halide.8 The halide can then attack an alkoxy group to give phosphonate ester and RX. An increase in temperature favors the Arbuzov reaction leading to phosphonates (Sn2 displacement). 

Scheme 1 Michaelis-Arbuzov (M-A) type of rearrangement in cationic polymerization of cyclic phosphonites.

These polymerizations proceed mostly by a Michaelis-Arbuzov (M-A) type of rearrangement (Scheme 1), involving cyclic phosphonium intermediates to produce poly-phosphinates or polyphosphonates (39). The presence of isomerized repeating units (40) was the result of the occurrence of side reactions. Sometimes the proportion of the isomerized units was higher than that of the normal units (39). ... 

Benzyl chloride, carbon tetrachloride, allyl chloride, and also 3-chloro-l-phenyl-1-propanone with triethyl phosphate and trimethyl phosphite in the presence of neutral alumina afforded the desired products in excellent yields with microwave irradiation. The t-butyl chloride failed in this condition and no Arbuzov rearrangement product was detected. The other types of alumina (acidic and basic) were not as effective as neutral alumina and usually give relatively low yields of the corresponding products. Simple work-up, low consumption of solvent, fast reaction rates, mild reaction condition, and good yields of the reaction make this method an attractive and useful contribution to the present methodologies. 

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