Applications of phosphorus III and V compounds as reagents in synthesis

Tervalent phosphorus has a high affinity for oxygen and the P=0 bond once formed is very strong. This fact, which also provides the driving force for the Wittig and related reactions, has led to the widespread use of P(III) compounds for direct deoxygenation of epoxides, ozonides, carbonyl compounds, and both N- and 5-oxides.2 

The deoxygenation of epoxides is not of great preparative value since it involves some loss of stereochemical integrity and the alkenes produced are more readily approached in other ways. Reductive cleavage of ozonides, for example, using triphenylphosphine, commonly forms part of the ozonolysis procedure for conversion of alkenes into carbonyl compounds. If a carbonyl compound is treated with an appropriate P(III) reagent then the reverse process may occur—reductive coupling to form a new C=C double bond. This has found a particularly important 

Caution This protocol must be undertaken in an efficient hood, and disposable vinyl gloves and chemical-resistant safety goggles must be worn at all times. 

To a plastic bucket (10 L), add sodium hypochlorite solution (500 mL) and liquid soap (10 mL) and make up to two-thirds full with hot water. This solution will be used at the end of the procedure to dispose of the waste and decontaminate used equipment. 

Place 2,5,7,9-tetrathiabicyclo[4.3.0]non-1 (6)-en-8-one 3 (0.50 g, 2.4 mmol), dry triethyl phosphite (20 mL) and a magnetic stirrer bar in a single-necked, round-bottomed flask (50 mL). Equip the flask with a reflux condenser and nitrogen inlet. Flush out the system thoroughly with dry nitrogen. 

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