Diethylaluminum Thiophenoxide1

Et2AlSPh

[58921-09-8]  · C10H15AlS  · Diethylaluminum Thiophenoxide  · (MW 194.30)

(preparation of O,S-acetals, catalyst for Claisen rearrangements;3,4 1,4-addition to vinyl epoxides7)

Solubility: sol hexane, toluene.

Form Supplied in: generated in situ from commercially available materials.

Preparative Method: prepared by the reaction of Triethylaluminum in toluene with 1.2 equiv of Thiophenol (0 °C, 20 min),2 or similarly in hexane solution (25 °C, 20 min).3

Handling, Storage, and Precautions: moisture sensitive. It is typically prepared in situ and used directly. Use in a fume hood.

Claisen Rearrangement.3,4

Allyl vinyl ethers undergo Claisen rearrangement in the presence of 2.5 equiv of the title reagent in 67-86% yields under extremely mild conditions (15 min to 1 h, 25 °C), as shown in eq 1. Similar results are obtained with Diethylaluminum Chloride-Triphenylphosphine, but no rearrangement is observed with Et2AlSEt. The (E/Z) selectivity is not impressive; better selectivity is observed with sealed tube thermolyses.4

1,3-Cycloalkanediones.5

d-Alkylidene-d-lactones and an ε-alkylidene-ε-lactone have been converted to 1,3-diones, probably via aluminum enolates (eq 2). These reactions are also effected with dimethylaluminum thioethoxide and Dimethylaluminum Methylselenolate, but less effectively with iodomagnesium thiophenoxide and lithium thiophenoxide.

O,S-Acetals.2,6

Acetals have been cleanly converted to O,S-acetals in 63-89% yields using diethylaluminum thiophenoxide (eqs 3-5).

Reaction with Vinyl Epoxides.7

The reagent adds regio- and stereoselectively to vinyl epoxides in 1,4-fashion to afford (Z)-4-phenylthio-2-buten-1-ols at rt (eq 6). Performing the reaction at -78 °C in toluene or using polar solvents such as ether and THF results in much reduced regio- and stereoselectivity. This stereoselectivity complements the reaction of the same vinyl epoxides with Thiophenol and Triethylamine in methanol, which gives almost exclusively the (E)-isomer. The products can be alkylated at the 4-position or converted into furans by oxidation with Lead(IV) Acetate.

Rearrangement of Pinacol Monoacetates.8

Upon treatment with the title reagent, vicinal diol derivatives afford rearrangement products with different regioselectivity when compared to acid-catalyzed pinacol rearrangement. For example, 1,1-diphenyl-2-acetoxy-1-hydroxypropane affords 72% of 2-phenylpropiophenone and 24% of 2,2-diphenylacetone, while 1,1-diphenyl-1,2-dihydroxypropane affords 80% of 2,2-diphenylacetone as the sole product upon acid catalysis (eqs 7 and 8).

2-Methyl-5-methylene-2-vinyltetrahydrofuran and 2,5-dimethyl-2-vinyl-2,3-dihydrofuran afford 3-methyl-1-phenylthio-2-hepten-6-one (eq 9).9


1. Fieser, M. FF 10, 281; 11, 542; 12, 343.
2. Masaki, Y.; Serizawa, Y.; Kaji, K. CL 1985, 1933.
3. Takai, K.; Mori, I.; Oshima, K.; Nozaki, H. BCJ 1984, 57, 446.
4. Takai, K.; Mori, I.; Oshima, K.; Nozaki, H. TL 1981, 22, 3985.
5. Tomioka, H.; Oshima, K.; Nozaki, H. TL 1982, 23, 99.
6. Masaki, Y.; Serizawa, Y.; Nagata, K.; Oda, H. TL 1986, 27, 231.
7. Yasuda, A.; Takahashi, M.; Takaya, H. TL 1981, 22, 2413.
8. Kanemoto, S.; Morizawa, Y.; Oshima, K.; Nozaki, H. BCJ 1982, 55, 3941.
9. Mori, I.; Takai, K.; Oshima, K.; Nozaki, H. T 1984, 40, 4013.

Joong-Kwon Choi

Korea Research Institute of Chemical Technology, Daejeon, Korea



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