Monofunctional chiral crowns. Part 1

Article abstract of DOI:10.1016/S0040-4020(01)86291-8

A siloxane oligomer bearing a chiral crown with high affinity for α-amino acids has been synthesised. The host is a modified form of a coronand first prepared by Cram, in which two 1,1'-binaphthol systems 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)(n)SiMe₂H] and [Me₃SiO(Me₂SiO)(x)(MeHSiO)(y)SiMe₃] with total chain lengths of ca 4 and 200 Si atoms respectively, via a Pt catalysed hydrosilylation reaction.