organophosphorus reagents in organic synthesis | …
Organophosphorus Reagents In Organic Synthesis By Cadogan
There are numerous instances in which this reaction has been carried out in organic synthesis, and only a few representative examples are given here.
Organophosphorus reagents in organic synthesis / edited by J.I.G
Elimination of triphenylphosphine and cyclization of the ester affords coumarin derivatives (eqs 10 and 11).The reagent is sufficiently nucleophilic to be alkylated with reactive electrophiles to produce phosphorus reagents often suitable for further reactions. Hydrolysis of the triphenylphosphorus and ester moieties after alkylation affords the corresponding carboxylic acids (eq 12).Alternatively, alkylation of the phosphorane with an -halo ketone is followed immediately by elimination of triphenylphosphine to give an ,-unsaturated -keto ester. This reaction has been used in the synthesis of isocardenolides (eq 13).The ylide can be halogenated or sulfenylated to prepare more complex ylides, which can then undergo Wittig reactions to yield vinyl halides or vinyl sulfides, respectively.