Methane, Tetrabromo

Since the yield of 161 is only 20%, the overall yields of the cycloadducts with reference to 1,3-cyclopentadiene are rather modest. Therefore, it was tested whether or not 6,6-dibromobicyclo[3.1.0]hex-2-ene (168) is after all stable enough to serve as progenitor of 162. To that end, dibromocarbene was generated from tetrabromo-methane by methyllithium [90] at -60 °C in the presence of 1,3-cyclopentadiene. Low-temperature NMR spectra revealed that 168 remains intact in the solution up to 0 °C. On the basis of this observation, a one-pot procedure was developed for the synthesis of the trapping products of 162 from 1,3-cyclopentadiene. As illustrated in Scheme 6.37, 168 was prepared at -60 °C, then an allenophile and methyllithium in succession were added to the mixture at -30 °C. In this way, the adducts of 162 to... 

The bromoallene (-)-kumausallene (62) was isolated in 1983 from the red alga Laurencia nipponica Yamada [64a], The synthesis of the racemic natural product by Overman and co-workers once again employed the SN2 -substitution of a propargyl mesylate with lithium dibromocuprate (Scheme 18.22) [79]. Thus, starting from the unsymmetrically substituted 2,6-dioxabicyclo[3.3.0]octane derivative 69, the first side chain was introduced by Swern oxidation and subsequent Sakurai reaction with the allylsilane 70. The resulting alcohol 71 was protected and the second side chain was attached via diastereoselective addition of a titanium acetylide. The synthesis was concluded by the introduction of two bromine atoms anti-selective S -substitution of the bulky propargyl mesylate 72 was followed by Appel bromination (tetrabromo-methane-triphenylphosphine) of the alcohol derived from deprotection of the bromoallene 73. 

Synonyms Carbon bromide Tetrabromide methane Tetrabromo methane... 

Tetrabromo- methane 20 60 5 Limited resistance/Not >3 >0.5 >0 resistant Hostalen PP Hoechst Celanese Specimen 50X25X1 mm (2X1X0.04 in) from press-molded sheets to DIN 53455... 

Preparation of CosCCOigCSiCOHis was first reported by Seyferth et al. (8,9) from dicobalt octacarbonyl and tribromomethane or tetrabromo methane to yield the intermediates HCCogiCOlg and BrCCogiCOig, respectively. The latter are treated with trichlorosi-lane to obtain CoglCOlgCSiClg in up to 90% yield. Finally the chloride is converted to the triole by using water in benzene at 80° C. 

Biedermann and Jacobson, who first prepared thieno[2,3-6]-thiophene (1) in 1886, characterized it as a 2,3,4,5-tetrabromo derivative with m.p. 172°. Later Capelle reported the isolation of a dibromo derivative of thienothiophene 1 with m.p. 122.5°, which was shown by Challenger and Harrison to be 2,3,5-tribromothieno[2,3-6]thiophene (m.p. 123°-124°). Capelle also obtained a tetrabromide, m.p. 223°, by bromination of the product of reaction of acetylene with sulfur. The tetrabromide seems to be identical with that prepared from the product of reaction of methane, acetylene, and hydrogen sulfide, m.p. 229°-230°, and is evidently 2,3,5,6-tetrabromothieno[3,2-6j-thiophene. ... 

SYNS BROMID UHUCITY D CARBON BROMIDE METHANE, TETRABROMIDE METHANE, TETRABROMO- TETRABROMIDE METHANE TETRABROMOMETHANE... 

Carbon tetrabromide. Carbon tetrachloride. Chloroform 3 See methane, tetrabromo-See methane, tetrachloro- 0.00005 0.000577 - 0.49 -4.17... 

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