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Dehydration of Alcohols 2377 through a Nester-Faust spinning band column to yield 9.0 g. of diethyl methylmalonate (40%), b.p. 43-54°( 0.8 mm), and 11.0 g. of diethyl dichloromethylmethylmalonate (33%), b.p. 73-75°(0.5 mm.). A dark pot residue remained (4.0 g.). The infrared spectrum of the dichloro fraction was identical in all respects to that of the fraction formed in the sodium trichloroacetate run listed above.Reaction of Diethyl Methylsodiomalonate with Bromoform. The reaction was performed as in the chloroform run listed above. Sodium (2.0 g., 0.09 g.-atom), 100 ml. of anhydrous diethyl ether, and 17.0 g. (0.10 mole) of diethyl methylmalonate were utilized. On removal of the ether, bromoform (33.0 g., 0.13 mole) was added and on gentle warming a vigorous exothermic reaction occurred. The mixture was refluxed for 1 hr. and then filtered from the solid which separated. The mixture was concentrated under reduced pressure and distilled through the spinning band column to yield 8.0 g. of bromoform (26% recovery), b.p. 25-36°( 3.5 mm.); 5.0 g. diethyl methylmalonate (30%), b.p. 57-65°( 2.5 mm.); and 6.0 g. (20%) of diethyl dibromomethylmethylmalonate, b.p. 105-107°(2 mm.). A redistilled fraction had b.p. 105-107°( 2 mm.). A dark pot residue remained.

The synthesis of irans-2-(2-methylthiophenyl)cyclopropanecarboxylic acid (10) is described with the use of dimethyloxosulfonium methylide to introduce the cyclopropane ring into methyl irans-o-methylthiocinnamate. Acid-catalyzed dehydration of 2-chloro-5-hydroxy-4,5-dihydro-l-benzothiepin 1,1-dioxide gave 2-chloro-lbenzothiepin 1,1-dioxide, while reaction of p-toluenesulfonic acid and 2-chloro-5-hydroxy-4,5-dihydro-l-benzothiepin 1-oxide produced 1-chloronaphthalene. The latter product is explained by SO elimination from the dehydration product, 4-chloro-l-benzothiepin 1-oxide.

This paper describes some observations made during a study directed toward the synthesis of benzo [6] thiepin.The synthesis and structure of 5-hydroxy-2-chloro-4,5-dihydrobenzo[b]thiepin (VII) and its acetate (VIII) are reported. Treatment of VII with p-toluenesulfonic acid produced an ester (XI). In rationalizing the origin of XI, homoallylic resonance stabilization of the intermediate carbonium ion becomes important. Since carbonium ions appeared to promote a ring contraction, the pyrolysis of VIII was studied. The pyrolysis products were -chloronaphthalene and 1,1'-naphthyl disulfide, which suggested the intermediate formation of 2-chlorobenzo [6] thiepin. A reaction of extruded sulfur and 2-chloronaphthalene is reported.A number of papers dealing with the preparation and properties of thiepin derivatives have appeared during the past decade; however, the synthesis of benzo[6]-