It is a base, e . g ., for the deprotonation of ketones to form sodium enolates, phosphonium salts to form Wittig reagents, and formamidinium salts to form diaminocarbenes.
22.
The concept of in situ activation of the C-OH bond in phosphonium coupling has also been applied to cross coupling reactions of tautomerizable heterocycles and arenols using other types of activating reagents.
23.
As the first direct bond formation via C OH bond activation, phosphonium coupling offers a powerful and practical methodology for chemical synthesis that features operational simplicity, functionality compatibility, and broad substrate scope.
24.
Ephraim Katzir first used this method to synthesize poly-L-lysine by polymerizing N-carbobenzyloxy-?-N-carboxy-L-lysine anhydride and removing the carbobenzyloxy protecting group with phosphonium iodide.
25.
Marvel worked with a wide variety of compounds, including dialkyl mercury, hexa-substituted ethanes, dienynes, alkyl lithium and Grignard reagents, quaternary phosphonium, and ammonium compounds, preparing them and investigating their reactions.
26.
Cl 2 adds to PPh 3 to give triphenylphosphine dichloride ( [ PPh 3 Cl ] Cl ), which exists as the moisture-sensitive phosphonium halide, This reagent is used to convert alcohols to alkyl chlorides in organic synthesis.
27.
It was subsequently shown by De Deene " et al " in 2002 that other antioxidants could be used in the manufacture of normoxic gels including tetrakis ( hydroxymethyl ) phosphonium chloride, having first been suggested to Baldock by Billingham in 1996.
28.
"' Georg Wittig "'( June 16, 1897 & ndash; August 26, 1987 ) was a German chemist who reported a method for synthesis of alkenes from aldehydes and ketones using compounds called phosphonium ylides in the Wittig reaction.
29.
If Y is nitrogen, the reaction is referred to as the Sommelet Hauser rearrangement; if Y is oxygen, then it is called a 2, 3-Wittig rearrangement ( not to be confused with the well-known Wittig reaction, which involves a phosphonium ylide ).
30.
Furthermore, the nitrogen atom may be replaced by a phosphorus, arsenic, or antimony atom ( the heavier nonmetallic pnictogens ), creating a phosphonium ( ) or arsonium ( ) cation that can itself be substituted similarly; while stibonium ( ) itself is not known, some of its organic derivatives are characterised.
