Dimethylprop-2-ynylsulfonium

Dimethylprop-2-ynylsulfonium bromide, preparation, intermediate in furan synthesis, 53, 1... 

A. Dimethylprop-2-ynylsulfonium Bromide. A mixture of 6.2 g. (0.1 mole) of dimethyl sulfide (Note 1), 11.9 g. (0.1 mole) of 3-bromopropyne (Note 2), and 10 ml. of acetonitrile (Note 3) is stirred magnetically for 20 hours (Note 4) in a darkened 100-mi. round-bottomed flask (Note 6) fitted with a calcium chloride drying tube. The resulting white, crystalline mass is filtered with suction and washed with three 50-ml. portions of dry ether (Note 6) to give 16.4 g. (90%) of the sulfonium salt, m.p. 105-106°. This material may be used in the next step without purification but, if desired, it may be recrystallized from ethanol-ether (Note 7) with minimal loss to give a product melting at 109-110°. 

B. 3-Acetyl-2, 4-dimethylfuran. To a solution of 8.7 g. (0.087 mole) of acetylacetone (Note 8) in 175 ml. of 0.5.M ethanolic sodium ethoxide (0.087 mole), contained in a 500-ml. round-bottomed flask fitted with a condenser topped with a calcium chloride drying tube, is added a solution of 15.75 g. (0.087 mole) of dimethylprop-2-ynylsulfonium bromide in... 

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