Synthesis and α-adrenergic activity of 2- and 6-methyl-substituted (3,4-dihydroxyphenyl)-3-piperidinols

Synergistic Peptide and Gold Catalysis: Enantioselective Addition of Branched Aldehydes to Allenamides

The combination of a peptide catalyst and a gold catalyst is presented for enantioselective addition reactions between branched aldehydes and allenamides. The two catalysts act in concert to provide γ,δ‐enamide aldehydes bearing a fully substituted, benzylic stereogenic center – a structural motif common in many natural products and therapeutically active compounds – with good yields and enantioselectivities. The reaction tolerates a variety of alkyl and alkoxy substituted aldehydes and the products can be elaborated into several chiral building blocks bearing either 1,4‐ or 1,5‐ functional group relationships. Mechanistic studies showed that the conformational features of the peptide are important for both the catalytic efficiency and stereochemistry, while a balance of acid/base additives is key for ensuring formation of the desired product over undesired side reactions.

Fully diastereoselective synthesis of polysubstituted, functionalized piperidines and decahydroquinolines based on multicomponent reactions catalyzed by cerium(IV) ammonium nitrate

The cerium(IV) ammonium nitrate (CAN)-catalyzed, three-component reaction between primary amines, β-dicarbonyl compounds, and α,β-unsaturated aldehydes in ethanol heated to reflux, constitutes a general, one-pot synthesis of 1,4-dihydropyridines. Their reduction with sodium triacetoxyborohydride furnished piperidine derivatives bearing up to five substituents with full diastereoselectivity in a hitherto inaccessible stereochemical arrangement. The reaction proceeded with no significant loss of enantiomeric purity under mild reduction conditions that are compatible with several functional groups that are normally sensitive to reduction. Octahydroquinolin-5-one derivatives, which were prepared by a modified version of the initial multicomponent reaction, were not suitable substrates for the sodium triacetoxyborohydride mediated reduction, but they were transformed into the corresponding decahydroquinolines, including a precursor of the amphibian alkaloid pumiliotoxin C, by catalytic hydrogenation under a variety of conditions.

Spirotetrahydronaphthalene analogues of sympathomimetic catecholamines. Synthesis and adrenergic activity of 5,6- and 6,7-dihydroxy-3,4-dihydrospiro[naphthalen-1 (2H)-3'-piperidines]

The 5,6- (5a) and 6,7-dihydroxy-3,4-dihydrospiro[naphthalen-1 (2H)-3'-piperidine] (6a) and their N-isopropyl derivatives (5b and 6b), DDSNPs, were synthesized. These compounds can be viewed as the result of the combination of the structure of the 3-(3,4-dihydroxyphenyl)-piperidine 2a or 2b, with the structure of the corresponding 1-(aminomethyl)-5,6-dihydroxy-(3a or 3b) or 1-(aminomethyl)-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (4a or 4b), 1-AMDTNs. The new compounds (5a, b and 6a, b) were assayed for their alpha and beta adrenergic properties by means of binding experiments and functional tests and the results were compared with those obtained for catecholamines 1a, b and the previously described 3-(3,4-dihydroxyphenyl)piperidine (3-DPP; 2) and 1-AMDTNs (3, 4). Comparison of the affinity and activity data of novel derivatives with those of reference compounds 2, 3 and 4 shows a general low ability of DDSNPs 5 and 6 to interact with both alpha and beta- adrenoceptors.

Conformationally restrained analogues of sympathomimetic catecholamines. Synthesis and adrenergic activity of 5,6- and 6,7-dihydroxy-3,4-dihydrospiro[naphthalen-1(2H)-2',5'-morpholines]

The 5,6- (10a) and 6,7-dihydroxy-3,4-dihydrospiro[naphthalen-1(2H)-)-2',5'-morpholine](11a) and their N-isopropyl derivatives (10b and 11b) (DDSNMs), which can be viewed as the result of the combination of the structure of the 2-(3,4-dihydroxyphenyl)morpholine 5a or 5b (DPMs) with the structure of the corresponding 1-(aminomethyl)-5,6-dihydroxy- (8a or 8b) or 1-(aminomethyl)-6,7-dihydroxy-1,2,3,4-tetrahydro-1-naphthalen-ol (9a or 9b) (1-AMDTNs) were synthesised. The new compounds DDSNMs 10a,b and 11a,b were assayed for their alpha- and beta-adrenergic properties by means of binding experiments and functional tests and the results were compared with those obtained for catecholamines 1a, b and the previously described morpholine (5) and tetrahydronaphthalene (8, 9) derivatives. The affinity and activity indices thus obtained indicate in general a low ability of the new compounds 10 and 11 to interact with the alpha- and beta-adrenoceptors, which, in all cases, was lower than that of the corresponding morpholine (5) and tetrahydronaphthalene (8, 9) analogues.