2-Bromo-4-methylbenzaldehyde

C 2-Bromo-4-methylbenzaldehyde A 3-1. three-necked flask is equipped with an efficient stirrer, a dropping funnel (Note 2), and a thermometer. The aqueous 10% formaldoxime prepared in step A is placed in the flask, and to it are added 6 5 g (0.026 mole) of hydrated cupric sulfate, 1.0 g. (0 0079 mole) of sodium sulfite, and a solution of 160 g of hydrated sodium acetate in 180 ml. of water The solution is maintained at 10-15° by means of a cold-water bath and stirred vigorously. The neutral diazonium salt solution prepared in step B is slowly introduced below the surface of the formaldoxime solution (Notes 3 and 4). After the addition of the diazonium salt solution is complete, the stirring is continued for an additional hour and then the mixture is treated with 230 ml. of concentrated hydrochloric acid. The stirrer and the dropping funnel are replaced by stoppers, and the mixture is gently heated under reflux for 2 hours The flask is set up for steam distillation, and the reaction product is steam-distilled. The distillate is saturated with sodium chloride, extracted with three 150-ml portions of ether, and the ethereal extracts are washed successively with three 20-ml portions of a saturated sodium chloride solution, three 20-ml. portions of an aqueous 10% sodium bicarbonate solution, and again with three 20-ml portions of a saturated sodium chloride solution. 

The first, path (1), was straightforward since all N-aminohet-erocycles used in this work (Table V) were known, and methods for their preparation have been published. The majority of the sub-stituted-benzaldehydes used in this method were prepared according to the Beech (17) method as described (18) for the conversion of 2-bromo-4-toluidine into 2-bromo-4-methylbenzaldehyde. The method is of wide application and gave substituted benzaldehydes in 50-75% yield. The unavailability of certain (polyfluoroalkoxy)anilines precluded synthesis of corresponding aldehydes via this method. These were prepared from anisic acids (Chart III) or reduction of nitro-phenols. For example, conversion of meta-anisic acid into 3-(tri-... 

Problem 14,28. Draw structural formulas for each of the following compounds (a) 5-methyl-3-hexanone, (b) 4-methylpentanal, (c) 2-bromo-4-methylbenzaldehyde. 

Unsymmetric compartmental ligands that allow for the controlled synthesis of unsymmetric Ni2 or heterobimetallic NiM complexes have received particular attention.1876,1892 A wide range of such ligands derived particularly from 2-hydroxy-3-hydroxymethyl-5-methylbenzaldehyde and 2-hydroxy-3-hydroxymethyl-bromo-benzaldehyde has now been prepared and used for Ni com-plexation. These ligands have monopodal iminic pendent arms and either mono- or dipodal aminic pendent arms and the terminal donors of the pendent arms can be provided by pyridine, imidazole, and tertiary amino groups.1893-1897 Complexes are usually prepared by reaction of the requisite Ni11 salts with the preformed ligand. 

Problem 19.23 Prepare (a) 2-bromo-4-hydroxytoluene from toluene, (b) 2-hydroxy-5-methylbenzaldehyde from p-toluidine, (c) m-methoxyaniline from benzenesulfonic acid. ... 

Murakami et al. reported the total synthesis of (-)-(/ )-herbertenol via construction of the sterically-congested quaternary stereocenter by enantioselective C-C bond cleavage (Scheme 8.7) [26]. The symmetrical cyclobutanone 39 was prepared from 2-bromo-5-methylbenzaldehyde (38). Treatment of 39 with a catalytic amount of a rhodium(I)/SEGPHOS (5,5 -bis(diphenylphosphino)-4,4 -bi-l,3-benzodioxole) complex induced enantioselective cleavage of the prochiral C-C bond to produce indanone 40. Mechanistically, transmetalation of the boryl... 

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