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This work was supported by the National Science Foundation (CHE-9296055), the National Institutes of Health (GM 28384), PPG Industries, Sepracor Inc., Merck Research Laboratories, and the W. M. Keck Foundation. We thank Dr. Pui Tong Ho for many helpful discussions. K. B. S. is extremely grateful to Professor Tohru Fukuyama of Rice University for communication of his sulfonamide deprotection discovery [8] and generously suggesting we try it in our earlier osmium-[5] and selenium-catalyzed [9] processes. Taking his advice led us to encounter, serendipitously, these long-sought conditions for achieving catalytic turnover in the AA.
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Dedicated to the memory of Fèlix Serratosa
Abstract
The stereospecific cis addition of “TsN” and H2O yields α-hydroxy-N-tosylamines (see below). This osmium-catalyzed process, which depends on Chloramine-T as the nitrenoid source, is rendered asymmetric in the presence of cinchona alkaloid ligands. The selectivities for reactions of the six olefins studied range from 33% ee (cis-stilbene) to 81% ee (trans-methylcinnamate). The active agent is presumably the compound Os(O)3NTs shown in square brackets. (DHQ)2-PHAL = bis(dihydro-quininyl)phthalazine (see preceding communication).