Jeremiah P. Freeman

Stereocontrolled syntheses of some conformationally restricted analogs of serotonin

Abstract Syntheses of serotonin analogs 2 and 3 are described including a case of retention in the Mitsunobu reaction. An unusual stereoselectivity in a reductive amination sequence is also described. Dopamine and serotonin activity of the eight analogs has been determined.

The synthesis of 9-(1-azetidinyl)-1,2,3,4-tetrahydroacridine

Synthesis of analogue (2) of tacrine is described in which the primary amino group is replaced by the azetidine moiety. The synthesis was accomplished in two steps from the acridinone derivative 10. This involved conversion of 10 to triflate 11, followed by treatment with azetidine to give the target compound 2

Syntheses of 1,2-diamino and 1,2-aminoalcohol derivatives in the piperidine and pyrrolidine series as anti-amnesic agents.

Tacrine, one of the drugs available for Alzheimers disease based on the cholinergic approach, suffers from considerable toxicity. Many analogues of tacrine has been prepared which retain the pharmacologically rich aminopyridine or aminoquinoline motifs. The current research is a continuation of our efforts in the area of 11-aminobenzoquinolizidines (4) and 10-aminobenzoindolizidines (5) (cf. ref9). A serendipitous discovery led us to the biologically active open chain analogue 9, and we proceeded to elaborate on this molecule. Overall, the compounds we prepared were poor inhibitors of acetylcholinesterase as compared to tacrine. The single exception was compound 20 which exhibited an effect comparable to that of tacrine, but only at a dose in the order of 10(-3) M. However, despite the poor acetylcholinesterase inhibition by 9, this compound was found to be an effective antiamnesic agent.

Syntheses of benzoquinolizidine and benzoindolizidine derivatives as anti-amnesic agents.

Tacrine, one of the drugs available for Alzheimers disease based on the cholinergic approach, suffers from considerable toxicity. Many analogues of tacrine have been prepared which retain the pharmacologically rich aminopyridine or aminoquinoline motifs. The current research was undertaken to produce an acetylcholinesterase inhibitor by employing 11-aminobenzoquinolizidines (4) and 10-aminobenzoindolizidines (5) as templates. Thus, we aimed to achieve three goals relative to tacrine: eliminate the pyridine and quinoline moieties and render the molecule less flat. Overall, the compounds we prepared were poorer inhibitors of acetylcholinesterase compared to tacrine. The single exception was compound 6f which exhibited an effect comparable to that of tacrine, but only at a dose of the order of 10(-3) M. However, despite the poor acetylcholinesterase inhibition by 6b, this compound proved to be an effective anti-amnesic agent at 45 mg/kg dose.

Anticonvulsants related to U-54494 prepared from cis-1,2- and cis-2,3- diaminotetralin

Abstract cis-Diaminotetralins 4 and 10 were converted in 4 steps to benzologs of the novel anticonvulsant U-54494. Attempted alkylation of 4 and 10 with 1,4-dibromobutane provided mixtures of the bis-pyrrolidino compounds and starting free bases together with the desired mono- pyrrolidino compounds 5 and 11. Treatment of these mixtures with ethyl chloroformate followed by Chromatographic separation gave the carbamates 7 and 12. Reduction of these carbamates with LiAlH4 provided the N-methylamino compounds 8 and 14. Finally, benzamide formation gave rise to the analogs of U-54494, compounds 9 and 15.

Hydration of the 2-monoanil of 1,3-diphenylpropane-1,2,3-trione. Revised structure of the hydration product.

Abstract The base-catalyzed hydration of anil 1 affords O-benzoylmandelanilide ( 7 ) rather than hydroxylamine 2 as was previously reported.

The structure of 2,3,5-trisubstituted 2-pyrrolin-4-ones

Abstract Compounds previously reported to be 2,3,5-trisubstituted 2-pyrrolin-4-ones are shown to have 5,5′-dimeric structures.

Reductive methylation/phosphorylation of 3,4-diazacyclopentadienone N-oxides with trimethyl phosphite

Treatment of 2,5-diphenyl-3,4-diazacyclopentadienone 3-oxide and 3,4-dioxide with trimethyl phosphite results in N-deoxygenation and methylation and O-phosphorylation to produce dimethyl (1-methyl-3,5-diphenyl-4-pyrazolyl) phosphate.

Unusual C-C cleavage during reduction of a β-aminonitroalkene

Abstract An unusual ring cleavage product 3 , a diamine, was observed during LAH reduction of β-aminonitroalkene 1 .

Structure-activity-relationship pertaining to the north-west region of the kappa opioid agonist, U-50,488

Compound 2, an unsaturated analog of U-50,488, has been prepared and found to be an active analgesic. Modeling studies with U-50,488, compound 2 and four other unsaturated U-50,488 analogs (namely, 3, 4, 5, 6) have been performed and enable us to define the size and shape of the hydrophobic pocket of the kappa receptor with which the north-west part of the ligands interacts.