P Bromobenzaldehyde

This category of primary synthesis is extremely rare in the quinoxaline series, although a few examples have been reported in recent literature. Thus a mixture of neat 1,2-benzenediamine (331) and an excess of p-bromobenzaldehyde heated at 350°C for 5 min afforded (with aerial oxidation ) 2,3-bis(p-bromophenyl) quinoxaline (332) in 50% yield " " and analogs were made similarly but usually in poor to mediocre yield after separation from byproducts." " In addition, an... 

A one-pot synthesis of thiohydantoins has been developed using microwave heating [72]. A small subset of p-substituted benzaldehydes, prepared in situ from p-bromobenzaldehyde by microwave-assisted Suzuki or Negishi reactions, was reacted in one pot by reductive amination followed by cyclization with a thioisocyanate catalyzed by polystyrene-bound dimethyl-aminopyridine (PS-DMAP) or triethylamine, all carried out under microwave irradiation, to give the thiohydantoin products in up to 68% isolated yield (Scheme 16). 

Ohta s group investigated the heteroaryl Heck reaction of thiophenes and benzothiophenes with aryl halides [127] and chloropyrazines [128]. Addition of the electrophiles invariably took place at C(2) as exemplified by the formation of arylbenzothiophene 156 from the reaction of benzothiophene and p-bromobenzaldehyde [127]. As expected, the heteroaryl Heck reaction of 2-thienylnitrile, an activated thiophene, with iodobenzene afforded the arylation product 157 [129],... 

Bromo-4-acetaminotoluene, 593, 605 p-Bromoacetanilide, 577, 580 p - Bromoace tophenone. 726, 732 m-Bromo-p-acetotoluidido, 593, 605 3-Bromo-4-aminotoluene, 593, 605 hydrochloride, 605 p-Bromoanilides, 361 p-Bromoaniline, 577, 580 o-Bromoanisole, 404 p-Bromobenzaldehyde, 689, 694, 696 diacetate, 696... 

The submitters report that p-bromobenzaldehyde may be prepared by the same procedure, substituting 62 g. (0.37 mole)... 

Side-chain bromination occurs under the influence of light (cf. Expt 6.28) and the extent of bromination is controlled by ensuring that the bromine (used in the theoretical amount) is added no faster than the rate at which it is consumed. The halogen in the benzylidene halide is reactive and hydrolysis occurs readily under mild conditions. In the example cited (p-bromobenzaldehyde, Expt 6.118) the use of a boiling aqueous suspension of calcium carbonate gives good results. 

To a solution of 1.85 g of sodium in 40 ml of ethanol, was added 10 g of phthalide and 14.0 g of p-bromobenzaldehyde, and the reaction mixture was heated on the steam bath for one hour. Water was then added, and the alcohol was distilled off. Then after adding additional water, the reaction mixture was acidified with hydrochloric acid to precipitate the crude product, which was filtered off, dried and recrystallized from methanol. The 2-p-bromophenylindandione is in the form of dark red crystals, having a melting point of 133-135°C. 

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