Synthesis of enantiopure, trisubstituted cryptophane-A derivatives.

The efficient synthesis of enantiopure, trisubstituted cryptophane-A derivatives, organic host molecules with unusually high xenon affinity, is reported. Synthesis and chromatographic separation of (±) tri-Mosher's acid substituted cryptophane diastereomers gave ready access to the enantiopure cryptophanes, which are critical components in the design of enantiomerically pure (129)Xe biosensors. Hyperpolarized (129)Xe NMR spectroscopy identified single resonances for both trisubstituted cryptophane diastereomers that were separated by 9.

New F-18 prosthetic group via oxime coupling.

A novel fluorine-18 prosthetic ligand, 5-(1,3-dioxolan-2-yl)-2-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)pyridine [(18)F]2, has been synthesized. The prosthetic ligand is formed in high radiochemical yield (rcy = 71 ± 2%, n = 3) with excellent radiochemical purity (rcp = 99 ± 1%, n = 3) in a short reaction time (10 min). [(18)F]2 is a small, neutral, organic complex, easily synthesized in four steps from a readily available starting material.

Efficient syntheses of thiadiazole peptides.

Novel N-(Cbz-aminoacyl)thiosemicarbazides 3a-c were cyclized by treatment with sulfuric acid to give 1,3,4-thiadiazoles 4a-c. Compounds 4a-c reacted with N-(Cbz-aminoacyl)- and -dipeptidoylbenzotriazoles to afford chirally pure 1,3,4-thiadiazol-2-yl-substituted amino acids 6a-c and dipeptides 7a-c.

Benzotriazole-assisted solid-phase assembly of Leu-enkephalin, amyloid beta segment 34-42, and other "difficult" peptide sequences.

Microwave-assisted solid-phase syntheses of six "difficult" peptides, H-VVSVV-NH(2) (3), H-VVVSVV-NH(2) (4), H-VIVIG-OH (5), H-TVTVTV-NH(2) (6), H-VKDGYI-NH(2) (7), and H-VKDVYI-NH(2) (8), were achieved utilizing N-(Fmoc-alpha-aminoacyl)benzotriazoles. Extension to the syntheses of Leu-enkephalin (9) and amyloid-beta (34-42) (10) demonstrates that this strategy comprises an efficient route to new and known "difficult" peptides.

Microwave-assisted solid-phase peptide synthesis utilizing N-Fmoc-protected (alpha-aminoacyl)benzotriazoles.

A novel microwave-assisted solid-phase peptide synthesis utilizing N-Fmoc-protected(alpha-aminoacyl)benzotriazoles was applied in the preparation of tri-, tetra-, penta-, hexa-, and heptapeptides in 71% average crude yield.

C-aminoimidoylation and C-thiocarbamoylation of esters, sulfones, and ketones.

Esters, sulfones, and ketones were C-aminoimidoylated and C-thiocarbamoylated by benzotriazole-1-carboxamidines 8a-g and 1-(alkyl-or-arylthiocarbamoyl)benzotriazoles 9a-i, respectively. The present work represents the first systematic approach to these compound classes, the few previously known examples of which were obtained by diverse approaches.