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A series of beta-substituted and beta,beta-disubstituted N-acyl 5-methoxy-1-methyltryptamines and 5-methoxytryptamines have been prepared as melatonin analogues to investigate the nature of the binding site of the melatonin receptor. The affinity of analogues was determined in a radioligand binding assay using cloned human MT(1) and MT(2) receptor subtypes expressed in NIH 3T3 cells. Agonist and antagonist potency of all analogues was measured using the pigment aggregation response of a clonal line of Xenopus laevis melanophores. beta-Methylmelatonin (17a) and beta,beta-dimethylmelatonin (17b), though showing a slight decrease in binding at human receptors, show an increase in potency on Xenopus. N-Butanoyl 5-methoxy-1-methyl-beta,beta-trimethylenetryptamine (12c) is an antagonist at human MT(1) receptors but an agonist at MT(2), while N-butanoyl 5-methoxy-1-methyl-beta,beta-tetramethylenetryptamine (13c) is an antagonist at MT(1) but had no action at MT(2) and is one of the first examples of an MT(1) selective antagonist.

The combination of three reagents-a tridentate pybox ligand (pybox = pyridine bis(oxazoline)), magnesium perchlorate, and Hunig base (iPr 2EtN)-allows the catalytic generation of a chiral glycine enolate from 1 that undergoes highly enantioselective addition to a range of aryl aldehydes 2. The protected aryl β-hydroxy-α-amino acid products obtained include a protected version of one of the aryl serine units present in the glycopeptide antibiotic vancomycin.

A series of 7-substituted melatonin and 1-methylmelatonin analogues were prepared and tested against human and amphibian melatonin receptors. 7-Substituents reduced the agonist potency of all the analogues in the Xenopus laevis melanophore assay, 7-bromomelatonin (5d) and N-butanoyl 7-bromo-5-methoxytryptamine (5f) being the most active compounds, but both were 42-fold less potent than melatonin (1). Whereas all the analogues bind with lower affinity at the human MT(1) receptor than melatonin, 5d, 5f and N-propanoyl 7-bromo-5-methoxytryptamine (5e) show a similar binding affinity to melatonin at the MT(2) receptor and consequently show some MT(2) selectivity. These results suggest that the receptor pocket around C-7 favours binding by an electronegative group, suggesting an electropositive region in this area of the receptor.

The combination of three reagents-a tridentate pybox ligand (pybox = pyridine bis(oxazoline)), magnesium perchlorate, and Hunig base (iPr 2EtN)-allows the catalytic generation of a chiral glycine enolate from 1 that undergoes highly enantioselective addition to a range of aryl aldehydes 2. The protected aryl β-hydroxy-α-amino acid products obtained include a protected version of one of the aryl serine units present in the glycopeptide antibiotic vancomycin.

The combination of triethylamine, magnesium(II) perchlorate and bipyridine generates a catalyst system for the efficient combination of ethyl isothiocyanatoacetate and a range of aromatic aldehydes. The products of these reactions are synthetically valuable protected β-hydroxy α-amino acids.

The combination of triethylamine, magnesium(II) perchlorate and bipyridine generates a catalyst system for the efficient combination of ethyl isothiocyanatoacetate and a range of aromatic aldehydes. The products of these reactions are synthetically valuable protected β-hydroxy α-amino acids.