Theoretical and Experimental Studies of Asymmetric Organozinc Additions to Benzaldehyde Catalyzed by Flexible and Constrained γ-Amino Alcohols
摘要:
The cis-decalin based gamma-amino alcohols, 1-5, were synthesized, resolved, and employed as catalysts in the addition of organozincs to benzaldehyde. Despite large facial differentiation in the RZn adducts of the ligands, the enantioselectivities were found to be moderate. Transition structure calculations were done using several quantum chemical methods to examine the underlying causes of the selectivity for three gamma-amino alcohols, 1, 2, and 3. The tricyclic mu-oxo (6/4/4), rather than the bicyclic six-membered (6/6), transition structures were found to explain the observed enantioselectivity for 2 and 3. MP2 calculations gave the best correlation to the experimental results compared to B3LYP and HIP calculations. The conformational flexibility of the chiral ligands was found to be an important factor in the selectivity.
Hetero [f] fused carbocyclic pyridines as dopaminergic agents
申请人:Warner-Lambert Company
公开号:US04762843A1
公开(公告)日:1988-08-09
Hetero [f] fused carbocyclic pyridines are described, as well as methods for the preparation and pharmaceutical compositions of same, which are useful as dopamine agonists with selectivity for the presynaptic dopamine receptor and are useful as dopaminergic, antipsychotic and antihypertensive agents as well as for treating hyperprolactinaemia-related conditions and central nervous system disorders.
β-enaminones is presented: in the presence of tetraethyl orthosilicate, a number of highly functional β-enamino esters were obtained; this method provided an alternative for the formation of β-amino-α,β-unsaturated carbonyl compounds with mild and functional group compatible reaction conditions.
Rearrangements of Bicyclic Nitrones to Lactams: Comparison of Photochemical and Modified Barton Conditions
作者:Yibin Zeng、Brenton T. Smith、John Hershberger、Jeffrey Aubé
DOI:10.1021/jo035004b
日期:2003.10.1
The rearrangement of nitrones to lactams can be carried out by photochemical activation or by treatment with Tf(2)O followed by KOH-promoted rearrangement (a modification of conditions originally introduced by Barton). Substrates in which the nitrone is part of a fused bicyclic ring system have traditionally proven problematic for this kind of reaction. In this study, a series of mono-, bi-, and tricyclic
Dopamine autoreceptor agonists as potential antipsychotics. 3. 6-Propyl-4,5,5a,6,7,8-hexahydrothiazolo[4,5-f]quinolin-2-amine
作者:Bradley W. Caprathe、Juan C. Jaen、Lawrence D. Wise、Thomas G. Heffner、Thomas A. Pugsley、Leonard T. Meltzer、Masood Parvez
DOI:10.1021/jm00113a010
日期:1991.9
A series of rigid tricyclic analogues of the dopamine (DA) agonist PD 118440 [4-(1,2,5,6-tetrahydro-1-propyl-3-pyridinyl)-2-thiazolamine] was synthesized and evaluated for dopaminergic activity and DA autoreceptor selectivity. (R)-(+)-6-Propyl-4,5,5a,6,7,8-hexahydrothiazolo[4,5-f]quinolin-2-amine ((+)-6) was identified as the most selective DA autoreceptor agonist from this group of compounds. It inhibited spontaneous locomotor activity (LMA) in rodents, reversed the gamma-butyrolactone (GBL) induced accumulation of rat striatal DOPA and inhibited brain DA neuronal firing, all suggestive of direct DA autoreceptor agonist activity. However, (+)-6 is not completely free of postsynaptic DA activity, as evidenced by its stimulation of LMA in rats at high doses and its ability to produce stereotypy. On the other hand, (-)-6 appears to be a weak partial DA agonist with some effects on brain DA synthesis only at high doses. Like other DA autoreceptor agonists and DA antagonists, (+)-6 inhibited Sidman conditioned avoidance in squirrel monkeys, a test predictive of clinical antipsychotic activity. However, unlike classical antipsychotics, (+)-6 did not induce dystonias in haloperidol-sensitized squirrel monkeys, suggesting a minimal propensity toward extrapyramidal side effects (EPS).