Molecules (Aug 2023)

Access to Enantiomerically Pure <i>P</i>-Chiral 1-Phosphanorbornane Silyl Ethers

  • Kyzgaldak Ramazanova,
  • Soumyadeep Chakrabortty,
  • Fabian Kallmeier,
  • Nadja Kretzschmar,
  • Sergey Tin,
  • Peter Lönnecke,
  • Johannes G. de Vries,
  • Evamarie Hey-Hawkins

DOI
https://doi.org/10.3390/molecules28176210
Journal volume & issue
Vol. 28, no. 17
p. 6210

Abstract

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Sulfur-protected enantiopure P-chiral 1-phosphanorbornane silyl ethers 5a,b are obtained in high yields via the reaction of the hydroxy group of P-chiral 1-phosphanorbornane alcohol 4 with tert-butyldimethylsilyl chloride (TBDMSCl) and triphenylsilyl chloride (TPSCl). The corresponding optically pure silyl ethers 5a,b are purified via crystallization and fully structurally characterized. Desulfurization with excess Raney nickel gives access to bulky monodentate enantiopure phosphorus(III) 1-phosphanorbornane silyl ethers 6a,b which are subsequently applied as ligands in iridium-catalyzed asymmetric hydrogenation of a prochiral ketone and enamide. Better activity and selectivity were observed in the latter case.

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