Phosphorus Pentoxide in Organic Synthesis; XVII¹. A New Synthesis of 4-Arylamino-2, 3-polymethylenequinolines

Synthesis and AChE inhibitory activity of new chiral tetrahydroacridine analogues from terpenic cyclanones

“…It is noteworthy from a mechanistic viewpoint that an intermediate, probably enamine 6, was first formed, which then converted to tetrahydroacridine (Scheme 1). Among several catalysts reported in the literature, such as ZnCl 2 [48], AlCl 3 [49], P 2 O 5 [50], and BF 3 $Et 2 O [16], the catalyst of choice for this work was BF 3 $Et 2 O. As described in the literature, also in our hands, BF 3 $Et 2 O proved to be an effective catalyst for the cyclodehydratation reactions, giving the best overall yield and highest purity, using cyclohexanone and anthranilonitrile as the model substrate [16,34].…”

A Concise Construction of Polycyclic Quinolines via Annulation of ω-Cyano-1-alkynes with Diaryliodonium Salts

“…For example, bromoquinoline 3ae was transferred into tacrine in 69% yield via amination with ammonium catalyzed by Cu 2 O . Other transformation involving amination with toluidine, ethynylation with tolyl acetylene (Sonogashira coupling reaction), and arylation with m -tolyl boronic acid (Suzuki coupling reaction) worked also well under classic conditions and provided quinoline derivatives 4a – 4c . Analogously, bromoquinoline 3ab was aminated into 4d in 54% yield and arylated into 4e in 95% yield.…”

The Sandmeyer Reaction on Some Selected Heterocyclic Ring Systems: Synthesis of Useful 2-Chloroheterocyclic-3-carbonitrile Intermediates

“…Pyridine 20b [prepared by reacting 2-amino-6chloropyridine-3,5-dicarbonitrile (20a) 1 with allylamine] and 22, 17 without an aryl ring at C4 provided also the expected 2-chloro derivatives 21 and 23 18 in satisfactory yields ( Figure 2). Finally, tacrine (12), 19 a potent cholinergic agent, which has been employed for the treatment of Alzheimer's disease, under the same experimental conditions, afforded the known 9-chloro-1,2,3,4-tetrahydroacridine (25) in low yield ( Figure 2).…”