Synthesis and structure-activity relationship of C5-substituted analogues of (+-)-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine [(+-)-desmethyl-MK801]: ligands for the NMDA receptor-coupled phencyclidine binding site.
A series of eight C5-substituted analogues of (+-)-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (1) have been prepared by the directed lithiation-alkylation (and acylation) of its (+-)-N-tert-butylformamidinyl derivative 2 followed by formamidine solvolysis. An additional 10 analogues were prepared by elaboration of the C5-ethyl ester derivative. Analogues possessing large (e.g. propyl and larger) lipophilic substituents displace [3H]-1-(1-thienylcyclohexyl)piperidine [( 3H]TCP) from the high-affinity phencyclidine (PCP) binding site in rat brain homogenates only at high concentrations (Ki greater than 1000 nM); however, the presence of a polar amino functionality (e.g. 2-aminoethyl) offsets this effect (Ki = 20 nM). Thus, the boundary condition for lipophilic substituents larger than ethyl appears to be polar in nature. Interaction of the 11 relatively small (MR less than 14) C5-substituted analogues of 1 with the high-affinity PCP binding site associated with the N-methyl-D-aspartate (NMDA) receptor is best described by the equation log (1/Ki) = -5.83F + 0.64 pi + 7.41 (r = 0.90).
Monn
J A
JA
Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Thurkauf
A
A
Mattson
M V
MV
Jacobson
A E
AE
Rice
K C
KC
D000818:Animals; D001665:Binding Sites; D003986:Dibenzocycloheptenes / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D016291:Dizocilpine Maleate; D066298:In Vitro Techniques; D008024:Ligands; D010622:Phencyclidine / Q000031:analogs & derivatives / Q000378:metabolism; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects* / Q000378:metabolism*; D017478:Receptors, Phencyclidine; D012044:Regression Analysis; D013329:Structure-Activity Relationship
D003986:Dibenzocycloheptenes; D008024:Ligands; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D017478:Receptors, Phencyclidine; D016291:Dizocilpine Maleate; C012058:tenocyclidine; D010622:Phencyclidine