Bromo-dimethyl

Telluran(VI) Bromo-dimethyl-triiodo- E12b, 657 (Bromiodid-Add.)... 

Cobalt Bromo-dimethyl-tris-[trime-thyl-phosphan]- XIII/9b, 116... 

Mercuri-bis-(dimethyl-p-toluidine) is obtained when the above hjKlrate is treated with concentrated sodium thiosulphate, and when bromo-dimethyl-p-toluidine is heated with 1 5 per cent, sodium amalgam for forty-eight hours at 120° to 125° C., a little ethyl acetate being used as catalyst. It crystallises in colourless, glistening plates, M.pt. k)° C., sliglitly soluble in benzene. 

Bromo dimethyl Reagent prepared from Mc2S and Brj togive Me,S Br Br. sulphonium Phenol in CHjClj at ambient temp, and reagent stirred 4h. bromide Chlorinastion also with chloro analogue, McjS Cl CT... 

Replacement of iodine by bromine in this reaction leads to a mixture of cis-and fran -1-alkenyl bromides and the corresponding n-alkanal. After some experimentation, Hamaoka and Brown found that alkenylboronic acids can be converted into a-bromo dimethyl acetals by reaction with bromine and sodium methoxide in methanol at -78° ... 

Bromoetherification of alkenes can be achieved using NBS in the desired alcohol as the solvent. The reaction of 1,3-dichloropro-pene with NBS in methanol yields an a-bromo dimethyl acetal in the first step in a convenient synthesis of cyclopropenone. Using propargyl alcohol the reaction depicted in eq 22 has been extended to an annulation method for the synthesis of a-methy-lene-y-butyrolactones. Intramolecular bromoetherification and bromoamination reactions are generally very facile (eq 23). In natural products synthesis, bromoetherification has been used for the synthesis of cyclic ethers (by subsequent debromination, see... 

X CH3 from CgHjo (A) leaves CgH4, a phenyl fragment Compound A must be a dimethylbenzene isomer. Consequently, B must be a bromo(dimethyl) benzene isomer. The question for both is Which isomer To find the answers, it is useful to write down aU the possible options. For A, there are three isomers ortho-, meta-, andpara-dimethylbenzene (xylene Section 15-1). 

This method has been applied to the synthesis of 4-methyl (659), 4-aryl (416, 519, 659), 4,5-dimethyl (137, 220, 221), 4,5-dialkyl (229, 681), 4-methyl-5-O-acetoxyethyl) (229), 4-methyl-5-(j3-carbethoxyethyl) (229), 4-ary 1-5-bromo (579), and 2-chlorothiazoles from the corresponding a-thiocyanatoketones (Table 11-28). 

The reaction of 2 2 dimethyl 1 propanol with HBr is very slow and gives 2 bromo 2 methyl propane as the major product... 

S-(2a,5a,6b])-6-Bromo-3,3-dimethyl-7-oxo-4-thia-l-azabicyclo [3.2.0]heptane-2-carboxyhc acid... 

Penam P-Lactamase Inhibitors. Penam is the trivial name given derivatives of the penicillin nucleus (31) the chemical name of which is 4-thia-l-a2abicyclo[3.2.0]heptane. Table 6 gives activity data for a diverse group of penams. The report that 6-P-bromopeniciU.anic acid [26631-90-3] [2(3)-(2a,5a,6P)]-6-bromo-3,3-dimethyl-7-oxo-4-thia-l-a2abicyclo[3.2.0]heptane-2-carboxyhc acid, (31, R = Br, R =H, R" = R " = CH3) a potent... 

When large groups, such as phenyl, bromo, ethoxycarbonyl or nitro are attached at position 3, the principal products are l-alkylcinnolin-4(l/f)-ones. Cyanoethylation and acetylation of cinnolin-4(l/f)-one takes place exclusively at N-1. Phthalazin-l(2/f)-ones give 2-substituted derivatives on alkylation and acylation. Alkylation of 4-hydroxyphthala2in-l(2/f)-one with an equimolar amount of primary halide in the presence of a base leads to 2-alkyl-4-hydroxyphthalazin-l(2/f)-one and further alkylation results in the formation of 4-alkoxy-2-alkylphthalazinone. Methylation of 4-hydroxy-2-methyl-phthalazinone with dimethyl sulfate in aqueous alkali gives a mixture of 4-methoxy-2-methylphthalazin-l(2/f)-one and 2,3-dimethylphthalazine-l,4(2//,3//)-dione, whereas methylation of 4-methoxyphthalazin-l(2/f)-one under similar conditions affords only 4-methoxy-2-methylphthalazinone. 

The ease of displacing a chloro, bromo or iodo substituent in comparable pyrimidines by aminolysis is disappointingly similar. Using 2-halogeno-4,6-dimethyl- and 4-halogeno-... 

In view of the high price and other difficulties associated with the use of phosphoryl bromide, the transhalogenation of 2-chloro- and 2-chloro-4,6-dimethyl-pyrimidine (919) by treatment with inexpensive phosphorus tribromide to give their bromo analogues in >50% yield, assumes potential importance as a general method (67JCS(C)1204). 

In contrast to the 3-substituted products above, 4-chloro-, 4-bromo- and 4-iodo-isoxazoles are readily prepared by direct halogenation of the corresponding isoxazoles, from 4-isoxazolediazonium salts by the Sandmeyer reaction, or by reaction of hydroxylamine with a-halo- 8-dicarbonyl compounds (62HC(l7)l, p. 66, 63AHC(2)365). 3,5-Bis(dimethyl-amino)-4-fluoroisoxazole has been synthesized by reaction of (Me2NCO)2CHF with hydroxylamine (78BSB391). 

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