Zinc bromide as catalyst for the stereoselective construction of quaternary carbon: improved synthesis of diastereomerically enriched spirocyclic diols
作者:Yong Qiang Tu、Chun An Fan、Shi Kuo Ren、Albert S. C. Chan
DOI:10.1039/b006182o
日期:——
proved to be a facile and efficient catalyst for the stereoselective semipinacol rearrangement of α-hydroxy epoxides at room temperature. Of note are the presence in the product of two adjacent chiral carbon centers, particularly the creation of a stereoselective quaternary center, and the efficient synthesis of β-hydroxy ketones, including some with naturally occurring spiroalkane skeletons. As an
A highly stereoselective and enantioselective reduction of racemic spiro[4,4]nonane-1,6-dione catalyzed by an oxazaborolidine reagent is described. The asymmetric reduction of the racemic spirodiketones resulted in enantiomerically pure spirodiols which are useful chiralauxiliaries and also key intermediates for the synthesis of other highlyeffectivechiral ligands. The trans,trans- and cis,trans-spirodiols
Absoluteconfiguration and enantiomericpurities of some hydroxy-ketones and diols of spiro[4.4]nonane and 2,2′-spirobi-indan can be simultaneously determined by use of MTPA derivatives and a lanthanoid shift reagent.