Anticonvulsant activity of glycine-site NMDA antagonists. 2. trans 2-carboxy-4-substituted tetrahydroquinolines

Phosphine-catalyzed [5+1] annulation of β'-acetoxy allenoates: straightforward access to tetrahydroquinoline derivatives

An unprecedented phosphine-catalyzed [5+1] annulation of β'-acetoxy allenoates with 1,5-dinucleophiles has been developed, which provides novel and facile access to functionalized tetrahydroquinolines in good to high yields in the presence of PPh3 and K3PO4 under mild reaction conditions. Notably, it is the first report of β'-acetoxy allenoates acting as C1 synthons in Lewis base-catalyzed annulation reactions.

Enantioselective Synthesis of 2-Functionalized Tetrahydroquinolines through Biomimetic Reduction

Biomimetic asymmetric reduction of 2-functionalized quinolines has been successfully developed with the chiral and regenerable NAD(P)H model CYNAM in the presence of transfer catalyst simple achiral phosphoric acids, providing the chiral 2-functionalized tetrahydroquinolines with up to 99% ee. Using this methodology as a key step, a chiral and potent opioid analgesic containing a 1,2,3,4-tetrahydroquinoline motif was synthesized with high overall yield.

A facile and green preparation of 2,4-diarylpolyhydroquinolines

An efficient and environmentally benign procedure for the preparation of 2,4-diarylpolyhydroquinoline derivatives from 5,5-dimethylcyclohexane-1,3-dione, chalcones and ammonium acetate under microwave irradiation in a solvent-free manner is described in this paper.

Recent syntheses of 1,2,3,4-tetrahydroquinolines, 2,3-dihydro-4(1H)-quinolinones and 4(1H)-quinolinones using domino reactions

A review of the recent literature is given focusing on synthetic approaches to 1,2,3,4-tetrahydroquinolines, 2,3-dihydro-4(1H)-quinolinones and 4(1H)-quinolinones using domino reactions. These syntheses involve: (1) reduction or oxidation followed by cyclization; (2) S_NAr-terminated sequences; (3) acid-catalyzed ring closures or rearrangements; (4) high temperature cyclizations and (5) metal-promoted processes as well as several less thoroughly studied reactions. Each domino method is presented with a brief discussion of mechanism, scope, yields, simplicity and potential utility.

Development of a flexible strategy towards FR900482 and the mitomycins

FR900482 and the mitomycins are two intriguing classes of alkaloid natural products that have analogous biological mechanisms and obvious structural similarity. Both classes possess potent anticancer activity, a feature that has led to their investigation and implementation for the clinical treatment of human cancer. Given the structural similarity between these natural products, we envisioned a common synthetic strategy by which both classes could be targeted through assembling the mitomycin skeleton prior to further oxidative functionalization. Realization of this strategy with respect to FR900482 was accomplished through the synthesis of 7-epi-FR900482, which displayed equal potency relative to the natural product against two human cancer cell lines. With the challenging goal of a synthesis of either mitomycin or FR900482 in mind, several methodologies were explored. While not all of these methods ultimately proved useful for our synthetic goal, a number of them led to intriguing findings that provide a more complete understanding of several methodologies. In particular, amination via π-allyl palladium complexes for the synthesis of tetrahydroquinolines, eight-membered heterocycle formation via carbonylative lactamization, and amination through late-stage C-H insertion via rhodium catalysis all featured prominently in our synthetic studies.

Natural product inspired diversity oriented synthesis of tetrahydroquinoline scaffolds as antitubercular agent

An efficient natural product inspired diversity oriented syn thesis of tetrahydroquinoline analogues has been developed using the natural carbohydrate derived solid acid catalyst via multicomponent aza-Diels-Alder reaction of imine (generated in situ from aromatic amine and aldehyde) with dienophile in acetonitrile in a diastereoselective manner. The use of water as solvent reverses the diastereoselectivity toward the cis isomer. Interestingly, tricyclic pyrano/furano benzopyran with cis diastereoselectivity is obtained when salicylaldehyde is used as an alternative of aromatic aldehyde under the same condition. These synthesized quinolines and benzopyrans analogues have been evaluated for their Antitubercular activity against M. tuberculosis H₃₇Ra, and M. tuberculosis H₃₇Rv, and some of the analogues shows better activity profile than their natural product analogues. The protocol is not only mild, efficient, ecofriendly, but also involves reusable and biodegradable catalyst and provides route for both the diastereoisomer.

Synthesis of substituted 1,2-dihydroquinolines and quinolines from aromatic amines and alkynes by gold(I)-catalyzed tandem hydroamination-hydroarylation under microwave-assisted conditions

A method to efficiently prepare substituted 1,2-dihydroquinolines and quinolines by Au(I)-catalyzed tandem hydroamination-hydroarylation under microwave irradiation was developed. This method requires short reaction time (10-70 min) and has a broad substrate scope.

The first aza Diels-Alder reaction involving an alpha,beta-unsaturated hydrazone as the dienophile: stereoselective synthesis of C-4 functionalized 1,2,3,4-tetrahydroquinolines containing a quaternary stereocenter

The reaction between aromatic imines and methacrolein dimethylhydrazone in the presence of 10% indium trichloride affords in good to excellent yields biologically and synthetically relevant 1,2,3,4-tetrahydroquinolines bearing a hydrazone function at C-4 in a one-pot process that involves the formation of two C-C bonds and the stereoselective generation of two stereocenters, one of them quaternary, and this constitutes the first example of an alpha,beta-unsaturated dimethylhydrazone behaving as a dienophile in a hetero Diels-Alder reaction and the first vinylogous aza-Povarov reaction.

Asymmetric multicomponent reactions (AMCRs): the new frontier

Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review.

Chiral shift reagent catalyzed, diastereoselective imino Diels–Alder reaction — Synthesis of pyrazolyltetrahydroquinolines

A new, target oriented, highly diastereoselective synthesis of pyrazolyltetrahydroquinolines was attempted successfully. The chiral shift reagent Eu(tfc) was found to be a better choice for inducing diasteroselectivity.Key words: imino Diels–Alder reaction, chiral shift reagent catalyst, pyrazolyltetrahydroquinolines, diastereoselectivity, antibacterial activity.

Development of Polymer-supported π-Acid Catalysts

We reported that dicyanoketene acetals (DCKA), in which gem-dicyano groups of tetracyanoethylene (TCNE) are displaced with alkoxyl groups, function as pi-acid catalysts, and that a polymer (poly-DCKA-1) derived by copolymerization of a monomer, in which the alkoxyl group at the omega-position is modified with a styrene moiety, with ethyleneglycol dimethacrylate also shows high level of activities as a pi-acid. In this research, the effects of dicyanoketene ethylene acetal (DCKEA), polymers previously developed (poly-DCKA-1 and 2), new monomers, in which the alkoxyl group at the omega-position is modified with an ethereal moiety, and the corresponding polymers (poly-DCKA-3 and 4) were investigated on catalytic activities. Among the catalysts, the polymer (poly-DCKA-1) had the most efficient activity in monothioacetalization, cyanation, and Mukaiyama aldol reaction of acetals, two-component and three-component Mannich-type reaction, hydrolysis of acetals and silyl ethers, and two-component and three-component inverse electron demand Aza-Diels-Alder reaction. Remarkably, the polymer catalyst works more efficiently in water than in organic solvents and is recyclable.

A Silver-Catalyzed Domino Route toward 1,2-Dihydroquinoline Derivatives from Simple Anilines and Alkynes

[reaction: see text] A silver-catalyzed domino reaction of simple anilines and alkynes generates 1,2-dihydroquinoline derivatives efficiently.