5-Bromo-6- quinoxaline

Li and Yue also reported the intermolecular palladium catalyzed cross coupling reactions of bromo quinoxalines 214 and 216 with aryl boronic acids and heterocyclic stannanes, respectively <99TL4507>. The Suzuki couplings (i.e., 214 215) required the use of a... 

Synthesis and SAR studies have been done for a series of 2-aniino-3-heteroarylquinox-alines. The Stille reaetion of furylstannane with 2-aniino-3-bromo-quinoxaline 202 gave 2-furylquinoxaline 204 [99]. 

The bromination of 5,8-dimethoxyquinoxaline in methanol gives a mixture of 6-bromo and 6,7-dibromo compounds/ Treatment of 2-methylquinoxaline with bromine in acetic acid yields a mixture of 27% of 2 bromomethyl- and 37% of 2-dibromomethyl-quinoxaline." Thus in the absence of powerfully activating groups, side-chain rather than nuclear substitution takes place. 

The lipophilicity (7 m value) and specific hydrophobic surface area of pyrido[l,2-a]pyrazinium-l-olates 342 and -3-olate 343, and l-(4-chlorophe-nyl)-l-hydroxy-l,2-dihydropyrazino[2,l-a]isoquinolinium salt (344) has been measured by reversed-phase thin-layer chromatography (98MI13). Partition coefficient (log/ ) of 9-bromo-5-[(A-phenylaminocarbonyl)-methyl]-l,2,3,5,6,7-hexahydropyrido[l,2,3- fc]quinoxaline-2,3-dione was calculated to be 2.78 (97JMC4053). 

Ester group of l-(ethoxycarbonylmethyl)-7-aryl-5-oxo-1,2,3,5-tetrahydro-pyrido[l,2,3-i/e]quinoxaline-6-carboxamides was hydrolyzed and the 1-carboxymethyl moiety was converted to an aminocarbonylmethyl group with 1-methylpiperazine (01MIP12). Bromo atom of l-(2-bromoacetyl) derivatives was substituted by different amines. An amino group in the side chain attached to the position 1 of 7-aryl-5-oxo-l,2,3,5-tetrahydropyr-ido[l,2,3-i/e]quinoxaline-6-carboxamides was acylated, and terc-butoxycarbonyl protecting group of amino group was eliminated. 

Reaction of 10-bromo-iV,l,3-trimethyl-7-oxo-2,3-dihydro-7//-pyrido [ 1,2,3-i/e]quinoxaline-6-carboxamide with 2,6-dimethyl-4-(tributylstannyl)-pyridine in the presence of (Ph3P)2Pd(II)Cl in boiling toluene gave 10-(2,6-dimethyl-4-pyridyl) derivative (OOMIPIO). 

Reaction of ethyl 7-bromo-8-fluoro-l-(2-bromo-l-methylethyl)-4-oxo-l,4-dihydroquinoline-3-carboxylate with MeNH2 yielded 10-bromo-A, 1, 3-trimethyl-7-oxo-2,3-dihydro-7//-pyrido[l,2,3-<7e]quinoxaline-3-carboxamide (OOMIPIO). 

The second type is examplified in the condensation of 1,2-benzenediamine with dimethyl 3-bromo-3//-azirine-2,3-dicarboxylate to give dimethyl 2,3-quinoxaline-dicarboxylate (347) (Me2NCHO, 20°C, ultrasound, 2 h 69%) analogs were made likewise. 

Note These typical examples include both intra- and intermolecular cychza-tions, some of which do not directly involve the 0x0 substiment. 3-(a-Bromophenacyl)-2(l//)-quinoxalinone (102) gave 3-bromo-2-phenylfuro-[2,3-h]quinoxaline (103) (95% H2SO4, 65°C, 4 h 90% analogs likewise) a... 

Bromo-7-methoxy-5,8-quinoxalinequinone (148) and a-phenylstyrene (147) gave 5-phenylnaphtho[l,2-g]quinoxaline-7,12-quinone (150), probably via the intermediate (149) (PhH, pyridine, 20°C, hv, 30 min 12% analogs likewise but also in poor yield). 

Bromo-6-(2-imidazolin-2-ylamino)quinoxaline (brimonidine 119) afforded 5-bromo-6-guanidinoquinoxaline (120) as a major metabolite from several... 

Dimethoxy-6,7-dimethylquinoxaline gave a separable mixture of 6-bromo-methyl-2,3-dimethoxy-7-methylquinoxaline (165, R = H) and 6,7-bis(bromo-methyl)-2,3-dimethoxyquinoxaline (165, R = Br) [NBS, Bz202, CCI4, reflux, A, 14 h 54% and 16%, respectively] 46 6,7-dimethylquinoxaline similarly gave 6,7-bis(bromomethyl)quinoxaline (reflux, 4h 5()%).1043,cl 1 10,685... 

Bis(piperidinomethyl)quinoxaline 1,4-dioxide 6-Bromo-2,3-bis(bromomethyl)quinoxaline... 

Bromo-2,3-dimethoxy quinoxaline 6-Bromo-5,8-dimethoxy quinoxaline 6-Bromo-7,8-dimethyl-5-nitro-... 

Bromo-5,7,8-trichloroquinoxaline 6-Bromo-2,7,8-trimethyl-5-nitroquinoxaline 6-Bromo-3,7,8-trimethyl-5-nitroquinoxaline 6-Bromo-2,3,7-trimethylquinoxaline 6-Bromo-2,37-trimethylquinoxaline 1,4-dioxide 2-(But-1 -enyl)quinoxaline 2-Butoxy-3-chloroquinoxaline 2-sY r-BLiloxy-5-chloroc uinoxaline 2-Butoxy-3-hydrazinoquinoxaline... 

A Cu-catalyzed domino reaction has been developed by Cacchi and his group [305] for the synthesis of pyrrolo[2,3-b]quinoxalines 6/4-101 using a 2-bromo-3-tri-fluoroacetamido quinoxaline 6/4-98 and a tolane 6/4-99 containing electron-donating or -withdrawing groups as substrates, and with 6/4-100 as a proposed intermediate (Scheme 6/4.24). 

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