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.
A simple synthetic approach to homochiral 6- and 6′-substituted 1,1′-binaphthyl derivatives
作者:Heiko Hocke、Yasuhiro Uozumi
DOI:10.1016/s0040-4020(02)01584-3
日期:2003.1
Various homochiral binaphthyl derivatives having functional groups at the 6-position are important key intermediates for the immobilization of binaphthyl compounds on various solid-supports and have been prepared from commercially available 1,1'-bi-2-naphthol via controlled monopivalation of the 2-hydroxyl group and electrophilic aromatic substitution at the 6-position. (S)-2,2'-Bis-((S)-4-alkyloxazol-2-yl)-6-(2-methoxycarbonyl)ethyl-1,1'-binaphthyls (6-functionalized (S,S)-boxax)) were prepared and immobilized on various polymer supports including PS-PEG, PS, PEGA and MeO-PEG resin. (C) 2003 Elsevier Science Ltd. All rights reserved.