2- Bromophenyl ethyl ketone

Reductive desulphonylation of a-alkylidene fi-oxosulphones (typical procedure) To a solntion of NaTeH, prepared from tellurium (0.65 g, 5 mmol) and NaBH (0.45 g, 12 mmol) in EtOH (20 mL) under Nj, is added, while stirring, a solution of a-(p-bromoben-zylidene) )3-ketosulphone (0.73 g, 2 mmol) in DMF (15 mL). The solution, which immediately turns red-black, is stirred at room temperature for 3 h, and after addition of HjO (30 mL) is exposed to air for 30 min, to precipitate tellurium. The mixture is fdtered, the filtrate extracted with EtjO (3x40 mL) and the combined ether extracts dried (MgS04) and concentrated in vacuo to give the crude product, which is purified by SiOj chromatography (elution with benzene/EtOAc, 10 1), giving pure 2-(p-bromophenyl)ethyl phenyl ketone (0.46 g (80%) m.p. 65-66°C). 

An extremely simple one-pot synthesis of pyrazoles, pyrimidines, and isoxazoles has been realized by reacting enamino ketones, formed in situ with the appropriate bidentate nucleophile, under the action of microwaves [38]. Another approach to pyrazole from 4-alkoxy-l,l,l-trichloro-3-alken-2-ones and hydrazines, with toluene as solvent, is also possible under microwave conditions [39]. The Ullman coupling of (S)-[l-(3-bromophenyl)ethyl]ethylamine with N-H-containing heteroarenes such as pyrazole in N-methylpyrrolidone afforded the N-arylated compounds in high yields under microwave heating conditions at 198 °C [40]. 

Furthermore, as a related reaction, they obtained the cyclopentanol 79 by the Grignard-type reaction of l-methyl-2-(o-bromophenyl)ethyl phenyl ketone (78) without alkynes in the presence of Pd(OAc)2, PCy3, Na2C03 and 1-hexanol. It was confirmed that the addition of 1-hexanol was crucial [26]. These reactions are mechanistically interesting. A similar catalytic reaction has been reported by Vieente. These reactions are considered again in Chapter 3.7.2 [27]. 

In the reactions of aldehydes and ketones with ethyl A -(2-bromophenyl) imidates 297 in the presence of lithium, hydroxyimidates 298 were formed, the thermal cyclization of which in refluxing chlorobenzene resulted in formation of 4//-3,l-benzoxazines 299 in good yields (Scheme 55) <1996SC3167>. 

Also obtained by reaction of 2-bromophenyl propionate in a ethyl ether/hexane/ THF mixture at low temperature (-78 to -95°) with sec-butyllithium to give, after hydrolysis, the titled ketone (metal-promoted Fries rearrangement) (17%) [6590]. 

---