Benzylsulfonyldiazomethane1

[1588-80-3]  · C8H8N2O2S  · Benzylsulfonyldiazomethane  · (MW 196.22)

(safe, nonexplosive, shelf-stable substitute for diazomethane;2 performs similar reactions such as ring expansions3 and Arndt-Eistert syntheses;4 enables the preparation of various substituted benzyl sulfones)

Alternate Name: BSDM.

Physical Data: mp 98-99 °C; bright yellow solid.

Solubility: sol halogenated organic solvents.

Form Supplied in: not available commercially.

Preparative Methods: from the corresponding urethane via nitrosation with nitrosyl chloride followed by rearrangement on neutral alumina,2 or via reaction of ethyl benzylsulfonylacetate with tosyl azide in the presence of triethylamine.5

Handling, Storage, and Precautions: no toxicological data available; nonexplosive; stable for over 4 months at -20 °C. Use in a fume hood.

Diazomethane Substitute Reactions.

Many reactions of benzylsulfonyldiazomethane (BSDM) are analogous to those of Diazomethane, for which it was developed as a replacement. When treated with BSDM in the presence of Titanium(IV) Chloride, cycloalkanones are converted to the corresponding ring-expanded a-benzylsulfonyl ketones. These are then converted to the synthetically useful vinyl sulfones upon bromination followed by exposure to silver ion (eq 1).3 BSDM also serves well for the preparation of a-diazo a-sulfonyl ketones, which are Wolff rearrangement precursors (eq 2).6 The a-benzylsulfonyl diazo ketones are also convertible to a-sulfonyl esters by treatment with alcohols (eq 3).4

a-Substituted Sulfones.

When treated with Nitrosyl Chloride, BSDM affords three products, the major one being the a-chloro sulfone. The oxime, also produced, is of interest as a precursor to nitrile oxides (eq 4).1 Reaction with sulfenyl chlorides affords a-chloro a-sulfenyl sulfones (eq 5),7 while t-Butyl Hypochlorite in alcohol solvent enables the synthesis of a-alkoxy a-chloro sulfones, wherein the alkoxy substituent is derived from the solvent (eq 6).8 Finally, exposure of BSDM to p-Toluenesulfonic Acid provides the corresponding a-tosylate in 88% yield.5


1. van Leusen, A. M.; Strating, J. Q. Rep. Sulfur Chem. 1970, 5, 67.
2. van Leusen, A. M.; Strating, J. RTC 1965, 84, 151.
3. Toyama, S.; Aoyama, T.; Shioiri, T. CPB 1982, 30, 3032.
4. Kuo, Y.-C.; Aoyama, T.; Shioiri, T. CPB 1982, 30, 526.
5. Hua, D. H.; Peacock, N. J.; Meyers, C. Y. JOC 1980, 45, 1717.
6. Kuo, Y.-C.; Aoyama, T.; Shioiri, T. CPB 1982, 30, 2787.
7. Strating, J.; Reitsma, J. RTC 1966, 85, 421.
8. Zwanenburg, B.; Middelbos, W.; Hemke, G. J. K.; Strating, J. RTC 1971, 90, 429.

T. Howard Black

Eastern Illinois University, Charleston, IL, USA



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