Showing papers by "Jon Clardy published in 1982"
632 citations
132 citations
TL;DR: The results suggest that the properly oriented 1-phenyl substituent of 1 is important for dopamine-like activity; it may contribute to receptor binding by interaction with a chirally defined accessory site.
Abstract: Resolution of the unique dopamine receptor agonist 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (1) was achieved by a stereospecific multistep conversion of the readily separated enantiomers of its O,O,N-trimethylated precursor 2. The absolute stereochemistry of the antipodes of 2-MeI was determined by single-crystal X-ray diffractometric analysis, thus permitting assignment of the configuration of stereospecifically related 1, as well as that of the synthetic intermediates. High-performance liquid chromatography of diastereoisomeric derivatives was utilized to determine the enantiomeric excess of the R (greater than 97%) and S (greater than 89%) isomers of 1. Examination of the isomers in several in vitro and in vivo tests for both central and peripheral dopaminergic activity revealed that activity resided almost exclusively in the R isomer. The results suggest that the properly oriented 1-phenyl substituent of 1 is important for dopamine-like activity; it may contribute to receptor binding by interaction with a chirally defined accessory site. Configurational and conformational requirements for receptor binding of 1 are considered in relationship to previously described dopaminergic agents. These studies, in accord with previous suggestions, indicate that (R)-1 interacts with dopamine receptors in a conformation in which the catecholic hydroxyls and basic nitrogen are at least nearly maximally separated.
77 citations
TL;DR: The constitution and stereochemistry of 1, a yellow triterpenoid pigment isolated from a Somalian collection of the sponge Stelletta sp., has been unequivocally established by spectral and x-ray crystallographic methods as discussed by the authors.
60 citations
TL;DR: In this paper, the structures of the halogenated vinyl acetylenes, natural products from the red alga Laurencia pinnatifica (Gmal. Lamour) are described.
54 citations
TL;DR: In this paper, three new diketone cembrenolides have been isolated from the Pacific sea whip Lophogorgia alba using X-ray crystallography.
29 citations
TL;DR: An ichthyotoxic sesquiterpenoid of unusual structure, pacifigorgiol, has been isolated from the Pacific gorgonian caora Pacifigorgia adamsii as discussed by the authors.
28 citations
TL;DR: The structure and absolute stereochemistry of lemnalol (1), a ylangene-type sesquiterpenoid isolated from the soft coral Lemnalia tenuis Verseveldt, has been established by spectroscopic, chemical, and x-ray crystallographic analyses as discussed by the authors.
25 citations
TL;DR: In this article, the red alga Laurenciaintricata, collected in Bermuda, has yielded two new halogenated C-15 enynes, bermudenynol and its acetate.
Abstract: Extracts of the red alga Laurenciaintricata, collected in Bermuda, have yielded two new halogenated C-15 enynes, bermudenynol and its acetate. Spectroscopic evidence for the assignment of structures 1a and 1b to these compounds is presented. X-ray analysis verified the proposed structures and established their stereochemistry.
19 citations
TL;DR: Three Δ 3 -norcycloartene triterpenoids, with differing side chain functionalities, have been isolated from the tropical green alga Tydemania expeditionitis collected in Guam as discussed by the authors.
16 citations
TL;DR: In this article, a multistep conversion of the readily separated enantiomers of its O,O,N-trimethylated precursor 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (1) was achieved by a stereospecific multi-step conversion.
Abstract: Resolution of the unique dopamine receptor agonist 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (1) was achieved by a stereospecific multistep conversion of the readily separated enantiomers of its O,O,N-trimethylated precursor 2. The absolute stereochemistry of the antipodes of 2-MeI was determined by single-crystal X-ray diffractometric analysis, thus permitting assignment of the configuration of stereospecifically related 1, as well as that of the synthetic intermediates. High-performance liquid chromatography of diastereoisomeric derivatives was utilized to determine the enantiomeric excess of the R (greater than 97%) and S (greater than 89%) isomers of 1. Examination of the isomers in several in vitro and in vivo tests for both central and peripheral dopaminergic activity revealed that activity resided almost exclusively in the R isomer. The results suggest that the properly oriented 1-phenyl substituent of 1 is important for dopamine-like activity; it may contribute to receptor binding by interaction with a chirally defined accessory site. Configurational and conformational requirements for receptor binding of 1 are considered in relationship to previously described dopaminergic agents. These studies, in accord with previous suggestions, indicate that (R)-1 interacts with dopamine receptors in a conformation in which the catecholic hydroxyls and basic nitrogen are at least nearly maximally separated.
TL;DR: Neoirieone, a dibrominated diterpenoid of a new skeletal class related to the irieol Diterpenoids, has been isolated from Laurencia cf. irieii and its structure was elucidated by x-ray crystallographic analysis of its corresponding reduction product.
TL;DR: Aus der Rotalge Laurencia pinnatifida werden cis-Pinnatenin (I), das trans-Isomere (II) and das acyclische Trienin (III) isoliert as mentioned in this paper.
Abstract: Aus der Rotalge Laurencia pinnatifida werden cis-Pinnatifidenin (I), das trans-Isomere (II) und das acyclische Trienin (III) isoliert.