4- Bromo-1,2-dimethoxybenzene

The cryptostylines and their analogues have been used as pharmacological probes, such as the Dj dopamine receptor, an antagonist of substance P, and a peptide neurotransmitter. Propose a catalytic asymmetric synthesis of (S) (+) cryptostyline II starting from methyl 2 (2 formyl 4,5 dimethoxyphenyl)acetate and 4 bromo 1,2 dimethoxybenzene. 

Bromo-A/,2-dihydroxybenzamide 2-Bromo-1,4-dimethoxybenzene 4-Bromo-1,2-dimethoxybenzene... 

Overcharge tests were carried out in LiCo02 cathode half-cells that contained these additives, and a redox shuttle effect was observed between 4.20 and 4.30 V, close to the redox potentials of these additives. The same shuttling effect was observed even after 2 months of storage for these cells, indicating the stability and redox reversibility of these additives. A closer examination of the capacity retention revealed that 4-bromo-l,2-dimethoxybenzene seemed to have the best shuttle-voltage performance for the 4.0 V lithium cell used." The stability of these additives against reductive decomposition was also tested by the authors on metallic lithium as well as on carbonaceous anodes, and no deterioration was detected. 

Figure 46. Correlation between the voltage profiles and heat flow of a cell under overcharge cells with 100 mM 4-bromo-l,2-dimethoxybenzene (solid lines) and reference cell (dashed lines) (Reproduced with permission from ref 432 (Figure 17). Copyright 1999 The Electrochemical Society.)...

To a stirred solution of 19.8 g of 2-(n)-propylthio-l,3-dimethoxybenzene in 200 mL CH,C12 there was added 15.4 g elemental bromine dissolved in 100 mL CH2C1,. The reaction was not exothermic, and it was allowed to stir for 1 h. The reaction mixture was washed with H,0 containing sodium hydrosulfite (which rendered it nearly colorless) and finally washed with saturated brine. The solvent was removed under vacuum leaving 3 3.5 g of apale yellow liquid. This was distilled at 112-120 °C at 0.3 mm/Hg to yield 4-bromo-2-(n)-propylthio-l,3-dimethoxy-benzene as a pale yellow oil. Anal. (CnH 5Br02S) C,H. 

Sodium hydride (0.8 g) was added to 50 ml THE and diethylmalonate added over 5 minutes. l-Bromo-2,4-dimethoxybenzene (1.08 g) was then added in one portion and the reaction flask cooled to — 20°C. A few crystals of 1,10-phenanthroline were added as an indicator and the flask further cooled to —60°C. A few drops of n-BuLi were added until the brown color of the indicator persisted. Thereafter n-BuLi (3.05 mmol) and 0.91ml diisopropylamine was added to form lithium diisopropyl-amide. In order to observe a product conversion of 97%, a total of 2.5 ml EDA added drop wise via cannula in 24 minutes at —20°C to —24°C. The solution was acidified using 1.0 M HCl and the organic portion isolated, washed with brine and isolated in 93.2% purity as a yellow oil. H-NMR data supplied. 

C8H9Br02 1 -bromo-2,4-dimethoxybenzene 17715-69-4 25.00 1 5070 1 13760 C8H9N03 3-methyi-2-nitrobenzyl alcohol 80866-76-8 38.00 1.1820 2... 

Poly(oxy-l,4-phenylene) macromonomers were prepared in a one step Ull-mann type condensation of potassium 4-bromophenolate and l-bromo-2,5-dimethoxybenzene [189] (Scheme 56). 

This method has also been used for the iodination of phenols and for the bromination of anisole to give 4-bromoanisole (87%), of 1,3-dimethoxybenzene to give 4-bromo-L3-dimethoxybenzene (80%). 

The dimethoxybenzene nucleus of brucine (159), its methosulfate (82), dihydrobrucine (159), the brucinesulfonic acids (60, 93), pseudobrucine and its dihydro derivative (162, 165), iV-methyl-sec-pseudobrucine (168) as well as that of a number of transformation products of brucine (brucinonic acid (126), brucinolic acid (126), dihydrobrucinonic acid (126), bromo-dihydrodesoxybrucine (32), and dihydrodesoxybrucine (32)) is attacked by nitric acid (chromic acid in a few instances) at 0-5° with the formation of the respective o-quinones, which in turn may be reduced (SO2) to the respective colorless hydroquinones (or isomerized by HCl to colored isomers). More vigorous conditions (temperature and concentration of the oxidant) effect a simultaneous nitration of the quinone nucleus and a hydrolysis of the lactam grouping. 

A common intermediate in the synthesis of benzo[c]phenanthridines is the 2-aryl-l-tetralone, which provides rings A, B, and D of the alkaloid nucleus. In 1973, two independent research groups reported the synthesis of nitidine via the 3,4-dihydro-2-(3,4-dimethoxyphenyl)-6,7-methylenedioxy-(2/7)-naphthalone 29 (Scheme 2). The synthesis of this intermediate was arrived at by two different routes. Kametani ei al. (73JHC31) reduced 3-(3,4-methylenedioxyphenyl)proprionate 21 to the corresponding alcohol 22 with lithium aluminium hydride, which was then converted to the chloride 23 with thionyl chloride. After production of the nitrile 24 by reaction with sodium cyanide and subsequent hydrolysis to the carboxylic acid 25, Friedel-Crafts cyclization of the acid chloride 26 afforded the tetralone intermediate 27. Reaction with l-bromo-3,4-dimethoxybenzene 28 in the presence of sodium amide yielded the tetralone intermediate 29 in an overall yield of 4%. 

To a soiution of 27 mL diisopropyiamine in 150 mL anhydrous THF that was stirred under a N2 atmosphere and cooied to -10 °C with an externai ice/MeOH bath, there was added in sequence 83 mL of 1.6 M butyiiithium in hexane, 4.4 mL of dry CH3CN over the course of 5 min, and finaiiy 12.1 g of 4-bromo-2-ethyithio-1,3-dimethoxybenzene which had been dissoived in 20 mL THF (aiso added over the course of 5 min). The coior progressed from yeiiow to orange to deep red-brown. Stirring was continued for 10 min, and then the reaction mixture was... 

The solvent was removed under vacuum leaving 84 g of an amber oil as residue. This was distilled at 105-115 deg C at 0.15 mm/Hg yielding 73.3 g of 4-bromo-2-ethylthio-1,3-dimethoxybenzene as a light yellow oil. 

Preparation by anodic oxidation of 2-bromo-l,4-dimethoxybenzene followed by metallation ... 

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