Boron, tribromo

Boron tribromide Boron bromide (8) Borane, tribromo- (9) (10294-33-4) Trifluoroacetic acid Acetic acid, trifluoro- (8,9) (76-05-1)... 

Boron tribromide Boron bromide (8) Borane, tribromo- (9) (10294-33-4) Bromobis(dimethylamino)borane Borane, bromobis(dimethylamino)- (8) Boranediamine, 1-bromo-N,N,N, N -tetramethyl- (9) (6990-27-8) Tetrakis(dimethylamino)diboron Diborane(4), tetrakis(dimethylamino)- (8) Diborane(4)tetramine, octamethyl- (9) (1630-79-1)... 

The 6-membered B3O3 ring also occurs in many more complex borate anions. Cyclic boron-nitrogen molecules are considered later in this chapter. The cyclic molecule (c), X = SH, is the predominant species in the vapour of HBS2 at temperatures below 100°C. In the crystalline tribromo compound of type (c), (BrBS)3, the molecular structure (d) was found. 

The highly brominated diphenyl ether 54, isolated from the marine organism P. flava laysanica, was synthesized starting from 2,3,5-tribromo-4-methoxyphenol (55). Substrate 55 was electrolyzed at +610 mV V5. SCE (1 FmoF ) in 1 1 MeOH-CHCF containing AcOH-AcONITj and then submitted to zinc reduction leading to two dimers 56 and 57 in 26 and 43% yields, respectively. The former was demethylated with boron tribromide to give rise to the natural 54. 

Depending on the stoichiometric quantity of Br2 and the reaction temperature, electrophilic bro-mination of 1 with Brj in the presence of catalytic amounts of AICI3 gave 9-bromo-o-carborane (31, 95% yield), 9,12-dibromo-o-carborane (32), and 8,9,12-tribromo-o-carborane (33), as shown in Scheme 6.5 (Smith et al., 1965). Under similar reaction conditions, 1,2-dimethyl-o-carborane (28) was found to be tetrabrominated (34), presumably due to the electron donating effect of the methyl groups. 3-Bromo-o-carborane (35, 65% yield) was obtained by the reaction of 14 with a boron tribromide-methylsulflde complex [BBr3-S(CH3)3] (Li and Jones, 1990). 

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