60 2-オキサゾロンを構築材とする1、2-アミノアルコール類の効率合成(口頭発表の部)

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The 2-oxazolone moiety has proved of synthetic potential as an excellent leaving group in carboxyl- and phosphoryl-activating processes. This work deals with another synthetic aspects of the heterocycle as a building block for vic-amino・alcohol structures, which are structural units found in a substantial number of bioactive compounds such as enzyme inhibitors, antibiotics and sympathomimetic amines. The synthetic strategy shown in Fig.1 offers versatile routes to a wide variety of vic-amino alcohols in which the key step is regio- and stereoselective introductions of easily replaceable groups (X,Y) to the olefinic moiety of the 2-oxazolone (1), followed by stereospecific and stepwise substitutions with appropriate groups (R^2and R^3). This methodology would be expected to result in predominant formation of threo-derivatives (5), which could be readily converted, if needed, to erythro-configurations (6) by inversion of the hydroxy group via oxazoline intermediates (8 and 10). Enantiomerically pure type 2 synthons were readily obtained by bromo-methoxylation of (+)/(-)-3-ketopiny1-2-oxazolones with new reagent system, Br_2/MeC(OMe)_3/TMSOTf. The reactions were smoothly proceeded to result in highly diastereoelective formation of trans-5-bromo-4-methoxy adducts (2,90%de) which served as common intermediates for biologically significant vic-amino alcohols such as (16), (21) and (24).
天然有機化合物討論会の論文
1988-09-26