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Phosphite esters may be used as reducing agents in more specialised cases. For example, triethylphosphite is known to reduce certain hydroperoxides to alcohols formed by autoxidation [7] (scheme). In this process the phosphite is converted to a phosphate ester. This reaction type is also utilized in the Wender Taxol total synthesis.
Solvents are often not used for this reaction, though there is precedent for the improvement of selectivity with its usage. [5] Phosphonites are generally more reactive than phosphite esters. They react to produce phosphinates. Heating is also required for the reaction, but pyrolysis of the ester to an acid is a common side reaction. The poor ...
The phosphite esters and tertiary phosphines also effect reduction: ROOH + PR 3 → P(OR) 3 + ROH. Cleavage to ketones and alcohols occurs in the base-catalyzed Kornblum–DeLaMare rearrangement, which involves the breaking of bonds within peroxides to form these products.
Phosphites, sometimes called phosphite esters, have the general structure P(OR) 3 with oxidation state +3. Such species arise from the alcoholysis of phosphorus trichloride: PCl 3 + 3 ROH → P(OR) 3 + 3 HCl. The reaction is general, thus a vast number of such species are known.
The Perkow reaction. In the related Michaelis–Arbuzov reaction the same reactants are known to form a beta-keto phosphonate which is an important reagent in the Horner–Wadsworth–Emmons reaction on the road to alkenes. The Perkow reaction, in this respect is considered a side-reaction.
This reaction is a variant of the Michael addition: CH 2 =CHCO 2 R + 3 H 3 PO 3 → (HO) 2 P(O)CH 2 CH 2 CO 2 R. In the Hirao coupling dialkyl phosphites (which can also be viewed as di-esters of phosphonic acid: (O=PH(OR) 2) undergo a palladium-catalyzed coupling reaction with an aryl halide to form a phosphonate.
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
[4] [5] The reaction has since been extended to the synthesis of β-keto esters from the condensation between aldehydes and diazo esters. [6] The general reaction scheme is as follows: General Scheme for Buchner Reaction. The reaction yields two possible carbonyl compounds (I and II) along with an epoxide (III). The ratio of the products is ...