352556-22-0Relevant academic research and scientific papers
Chloroformamidinium salts: Efficient reagents for preparation of 2-aminobenzoimidazole, 2-aminobenzoxazole, and 2-aminobenzothiazole derivatives
El-Faham, Ayman,Chebbo, Mohamed,Abdul-Ghani, Mohamed,Younes, Ghassan
, p. 599 - 606 (2006)
A Reaction involving chloroformamidinium salts (TCFH 1a, BTCFH 1b, DmCFH 1c, DmPCFH 1d, BPCFH 1e) and 2-aminophenol 9a, benzene-1,2-diamine 9b, and 2-aminothiophenol 9c afforded 2-aminobenzoxazole 13, 2-aminobenzoimidazole 14, and 2-aminobenzothiazole 15 derivatives, respectively as major products, due to the in situ heterocyclization with dimethylamine acting as the better leaving group. Attempts for preparation of 13-15 from the reaction of N,N-dimethyl carbomyl chloride 16 with 2-aminophenol 9a, benzene-1,2-diamine 9b, and 2-aminothiophenol 9c were unsuccessful, and gave the unexpected products benzoxazol-2-ol 18a, benzoimidazol-2-one 18b, and S-(2-amino-phenyl) N,N-dimethylthiocarbamate 19 respectively. On the other hand reaction of chloroformamidinium salts 1a-e with 3-benzyl-2-hydrazinoquinoxaline 3 and 1-hydrazinophthalazine hydrochloride 4 in the presence of triethylamine as a base, afforded the [1,2,4]triazolo derivatives 6 and 7 respectively in good yield and purity. These triazole derivatives were formed due to the strong tendency towards heterocyclization and substitution of dimethylamine group as a better leaving group.
Palladium-copper catalyzed synthesis of benzofused heterocycles with two heteroatoms: Novel and highly regio- and stereoselective syntheses of (E)-2-(2-arylvinyl)-3-tosyl-2,3-dihydro-1,3-benzothiazoles and (E)-2-alkyl(aryl)idene-3,4-dihydro-2H-1,4-benzothiazines
Kundu,Nandi
, p. 4563 - 4575 (2007/10/03)
A highly novel, general, and convenient palladium and copper-catalyzed procedure has been developed for the synthesis of (E)-2-(2-arylvinyl)-3-tosyl-2,3-dihydro-1,3-benzothiazoles 28-40. 3-(2-Aminophenylthio)prop-1-yne 1 reacts with aryl iodides 2-14 under palladium-copper catalysis to yield the disubstituted alkynes 15-27 which after tosylation undergo a novel cyclization with CuI in the presence of triethylamine in THF to (E)-2-(2-arylvinyl)-3-tosyl-2,3-dihydro-1,3-benzothiazoles 28-40 rather than to the expected 3-alkylidene-4-tosyl-3,4-dihydro-2H-1,4-benzothiazines 41. The reaction is highly regio- and stereoselective. The synthesis of 2-(2-arylethyl)-3-tosylbenzothiazolines 42-47, 2-(2-arylvinyl)benzothiazoles 48-54, and a novel 5-substituted uracil derivative 55 of potential biological importance is also being reported. Similarly,the palladium-copper-catalyzed arylation of S-[2-(N-prop-2′-ynyl)aminophenyl]-N,N-dimethylthiocarbamate 58 with aryl iodides yields the disubstituted alkynes 59 which on cyclization with KOH in methanol leads to (E)-2-(2-aryl)methylidene-3,4-dihydro-2H-1,4-benzothiazines 61. The reaction of the diiodo compounds 12-14a, however, with 58 under palladium-copper-catalyzed reactions involves the participation of only one of the iodo groups in the heteroannulation process giving compounds 61i and 61j. These are amenable to further palladium-catalyzed reactions and afford polyunsaturated heteroaromatic compounds 62 and 63.
