A One-Pot–Three-Step Route to Triazolotriazepinoindazolones from Oxazolino-2<i>H</i>-indazoles
作者:Wayne E. Conrad、Kevin X. Rodriguez、Huy H. Nguyen、James C. Fettinger、Makhluf J. Haddadin、Mark J. Kurth
DOI:10.1021/ol3015804
日期:2012.8.3
A one-pot-three-step method has been developed for the conversion of oxazolino-2H-indazoles into triazolotriazepinoindazolones with three points of diversity. Step one of this process involves a propargyl bromide-initiated ring opening of the oxazolino-2H-indazole (available by the Davis-Beirut reaction) to give an N-1-(propargyl)-N-2-(2-bromoethyl)-disubstituted indazoione, which then undergoes -CH2Br -> -CH2N3 displacement (step two) followed by an uncatalyzed intramolecular azide-alkyne 1,3-dipolar cycloaddition (step three) to form the target heterocycle. Employing 7-bromooxazolino-2H-Indazole allows for further diversification through, for example, palladium-catalyzed coupling chemistry, as reported here.