摘要:
A siloxane oligomer bearing a chiral crown with high affinity for alpha-amino acids has been synthesised. The host is a modified form of a coronand first prepared by Cram, in which two 1,1'-binaphthol system are linked through the oxygen atoms at the 2,2'-positions to form a 22-membered ring system containing six ether oxygen atoms attached to each other by four ethylene units. This was selectively mono-alkenylated to form an undec-10-en-1-yl derivative, which was bonded to linear siloxanes [HSiMe2O(SiMe2O)nSiMe2H] and [Me3SiO(Me2SiO)x(MeHSiO)ySiMe3] with total chain lengths of ca 4 and 200 Si atoms respectively, via a Pt catalysed hydrosilylation reaction.