I. Synthesis of novel nonracemic cyclo-BINOLs and their applications. II. A new traceless linker for reverse direction solid phase peptide synthesis

A series of nonracemic, di- or mono-substituted cyclo-BINOLs has been constructed, the synthetic sequence being sufficiently general so as to offer many opportunities for a structural fine tuning of this important type of ligand for use in asymmetric catalysis. Nonracemic, di- or mono-substituted cyclo-BINOLs have been utilized to arrive at various di- or mono-substituted polymer-bound cyclo-BINOLs via attachment of a precursor ligand to formylated polystyrene resin. Efficacy has also been demonstrated for 1,2-addition of Et₂Zn to aryl aldehydes, as well as asymmetric oxidation of sulfides to sulfoxides.; A new chiral stationary phase (CSP) for liquid chromatographic separation of enantiomers was prepared by bonding a novel diastereomerically pure 3,3 ′-diphenyl-cyclo-BINOL-crown ether to silica gel. The resulting CSP was applied to the separation of enantiomers of various natural and unnatural α-amino acids.; Treatment of a free amino acid ester with CO₂ followed by exposure to a polymer-bound chlorosilane resulted in its attachment to the solid support. The newly formed silyl carbamate has been employed to build polypeptides via the carbonyl terminus. Cleavage of (poly)peptides using aqueous HF in acetonitrile led to its free amine from which was readily isolated as a Boc derivative. The poymer-bound linker could be reused very easily.