Aluminum Thiophenoxide1

Al(SPh)3

[15821-77-9]  · C18H15AlS3  · Aluminum Thiophenoxide  · (MW 354.49)

(used in preparation of phenylthioesters2 and ketene bis(phenylthio) acetals3)

Preparative Method: to a solution of 29 mL of 2.35 M Trimethylaluminum in hexane in 250 mL of deoxygenated xylene is added dropwise 20 mL of Thiophenol over a 5 min period. The solution is stirred at 25 °C for 10 min and heated at reflux for 48 h. The flask is transferred to a glove bag and the white solid is removed by filtration, washed with benzene, transferred to vials, and dried overnight in a vacuum desiccator.2

Handling, Storage, and Precautions: the reagent can be prepared as above and used directly as a suspension in xylene. Use in a fume hood.

Phenylthioesters.2

This reagent converts simple esters into phenylthioesters at 5 °C (4 h) or at 25 °C (1 h) in quantitative yields (eq 1).

The products from a,b-unsaturated esters are contaminated with 3-(phenylthio)thioesters, while using B(SPh)3 in refluxing xylene gave complementary results. A keto group at the 3-position inhibits the reaction while such a group at the 4-position leads to production of the thioacetal of the thioester when 2.5 equiv of the reagent are used.

For preparation of other thioesters, see also dialkylaluminum thiolates such as Diethylaluminum Thiophenoxide.

Ketene Bis(phenylthio) Acetals.3

Reaction of the title reagent with carboxylic acids or esters in refluxing benzene or xylene results in simple ketene bis(phenylthio) acetals. Yields are almost quantitative if the acid or ester is branched at the a- or b-position. When there is no branching at the a- or b-positions, an important byproduct is a tris(phenylthio) orthoacetate, a useful precursor of the ketene bis(phenylthio) acetal (eq 2).

Reaction of the reagent with a,b-unsaturated esters results in a 1,1,3-tris(phenylthio)-1-alkene in 70-85% yield (eq 3).


1. Fieser, M. FF 1981, 9, 15.
2. Cohen, T.; Gapinski, R. E. TL 1978, 4319.
3. Cohen, T.; Gapinski, R. E.; Hutchins, R. R. JOC 1979, 44, 3599.

Joong-Kwon Choi

Korea Research Institute of Chemical Technology, Daejeon, Korea



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