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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 Seyferth–Gilbert homologation is a chemical reaction of an aryl ketone 1 (or aldehyde) with dimethyl (diazomethyl)phosphonate 2 and potassium tert-butoxide to give substituted alkynes 3. [1] [2] Dimethyl (diazomethyl)phosphonate 2 is often called the Seyferth–Gilbert reagent. [3] The Seyferth–Gilbert homologation
The Perkow reaction is an organic reaction in which a trialkyl phosphite ester reacts with a haloketone to form a dialkyl vinyl phosphate and an alkyl halide. [1] The Perkow 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.
[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 ...
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.
When aliphatic alcohols are used the HCl by-product can react with the phosphate esters to give organochlorides and a lower ester. O=P(OR) 3 + HCl → O=P(OR) 2 OH + RCl. This reaction is usually undesirable and is exacerbated by high reaction temperatures. It can be inhibited by the use of a base or the removal of HCl through sparging.