Synthesis of benzannulated spiroacetals using chiral gold–phosphine complexes and chiral anions
摘要:
The development of an asymmetric gold-catalysed dihydroalkoxylation strategy for the synthesis of the 3'H-spiro[chroman-2,1'-isobenzofuran] spiroacetal ring system 5 is described. Spiroacetal was generated in up to 87:13 enantiomeric ratio using chiral gold-phosphine complexes and chiral silver phosphate Ag(S)-TRIP. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.
Synthesis of 6,6-bisbenzannulated spiroketals related to the rubromycins using a double intramolecular hetero-Michael addition (DIHMA)
摘要:
The synthesis of a series of 6,6-bisbenzannulated spiroketals using a novel microwave-assisted DIHMA approach is reported. Coupling of ail aryl acetylene and an aryl aldehyde via acetylide anion addition resulted in the formation of an alkynol which was followed by oxidation to the desired ynone. Spirocyclization using the DIHMA Protocol afforded the desired bisbenzannulated spiroketal in good yield. (C) 2009 Elsevier Ltd. All rights reserved.