Enantioselective Synthesis of Bridged Bicyclic Ring Systems
作者:John A. Brailsford、Liang Zhu、Mandy Loo、Kenneth J. Shea
DOI:10.1021/jo701964b
日期:2007.11.1
bicyclo[5.3.1]undecane and bicyclo[4.3.1]decane ringsystems. These structures are common to a number of biologically important natural products. Asymmetric variants of the type 2 IMDA reaction incorporating oxazolidinone chiral auxiliaries have been evaluated. This study has resulted in systems that deliver bridged bicyclic [5.3.1] and [4.3.1] ringsystems in high diastereomeric (97−99% de) and enantiomeric
Cationic iron(III) porphyrin was found to be an efficient catalyst for the highly chemoselective hetero-Diels Alder-type reaction of aldehydes with 1,3-dienes. The catalyzed process did not require the use of electron-deficient aldehydes such as glyoxylic acid derivatives or activated electron-rich 1,3-dienes such as Danishefslcy's diene and Rawal's diene. The high functional group tolerance and robustness of the catalyst were demonstrated. Further, the potential utility of the catalyst was demonstrated by performing the cycloaddition in the presence of water and by carrying out cycloaddition of an unactivated ketone such as cyclohexanone with a diene.