Resolution, absolute configuration, and synthetic transformations of 7-amino-tetrahydroindazolones
作者:Inta Strakova、Ilze Kumpiņa、Vitālijs Rjabovs、Jevgeņija Lugiņina、Sergey Belyakov、Māris Turks
DOI:10.1016/j.tetasy.2011.03.010
日期:2011.4
The chiral resolution of 7-amino-1-aryl-4,5,6,7-tetrahydro-indazol-4-ones was achieved via salt formation with O,O'-dibenzoyl tartaric acid. The transformation of enantiomerically enriched 7-amino-THIs into their corresponding azides proceeds with no decrease in their ee's. A comparison of the X-ray structures of the racemic and enantiopure forms of the title compounds explains the rather large melting point differences between both the series. The enantiopure azides obtained from the corresponding 7-amino-THIs were employed in copper-catalyzed Huisgen 1,3-dipolar cycloaddition reactions with various alkynes. The use of enantiomerically enriched THI scaffolds is demonstrated by the preparation of diastereomerically pure products when the former are conjugated with alkynes arising from natural sources. (C) 2011 Elsevier Ltd. All rights reserved.