Conformational preferences of oxy-substituents in butenolide–tetrahydropyran spiroacetals and butenolide–piperidine spiro-N,O-acetals
作者:Sébastien Naud、Sarah J. Macnaughton、Bryony S. Dyson、Daniel J. Woollaston、Jonathan W. P. Dallimore、Jeremy Robertson
DOI:10.1039/c2ob06849d
日期:——
of a series of oxy-substituted butenolide spiroacetals and spiro-N,O-acetals by oxidative spirocyclisation of 2-[(4-hydroxy or 4-sulfonamido)butyl]furans. The axial–equatorial preference of each oxy-substituent is investigated (NMR) by an acid-catalysed thermodynamic relay of configuration between the spiro- and oxy-centres. The axial site is preferred for most oxy-substituents at synthetically useful