1.
Adeyemi, Ahmed, 1986-
(författare)
Palladium(0)-Catalyzed Synthesis of Spirocycles and Supercritical Chemistry using a Resistively Heated Flow Reactor
2020
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
This doctoral thesis focusses on an effective and selective approach to the synthesis of spirocycles using palladium(0)-catalyzed Mizoroki-Heck reactions. In addition, selective and efficient chemistry was highlighted by the design and evaluation of a novel resistively heated system for continuous flow (CF) synthesis for high-temperature and high-pressure applications.Paper I described the design and evaluation of a novel resistively heated CF system. The design of a low-cost, simple, robust, and effective CF system involving a resistively heated steel reactor capable of delivering 400 °C and 200 bar was reported. The reactor was evaluated with esterification, transesterification and direct carboxylic acid to nitrile conversions using supercritical ethanol, methanol and acetonitrile respectively. Diels-Alder reactions under neat conditions were also carried out at high temperature and pressure.Paper II reported the synthesis of spirooxindoles by a selective application of the palladium(0)-catalyzed Mizoroki-Heck spirocyclization. The precursors for the reaction were synthesized by coupling 2-iodoanilines with esters derived from enantiomerically pure (+)-Vince lactam decorated with the bulky, directing 2,5-dimethylpyrrole protecting group. Ten different spirooxindoles were reported with good yields and high regio- and stereoselectivity. Functionalization of a synthesized spirooxindole was done by a palladium(0)-catalyzed alkoxycarbonylation, followed by selective deprotections.In Paper III, ether precursors were synthesized from (+)-Vince lactam, via a Mitsunobu reaction with the corresponding iodophenols. The precursors were later subjected to conditions for intramolecular Mizoroki-Heck reaction. Overall, 12 spiroethers were synthesized in useable yields, regioselectivity up to 98% and with excellent diastereoselectivity (d.e.>98%). Further functionalization to mono-protected rigidified amino acids was also demonstrated.
2.
3.
Wangsell, Fredrik, et al.
(författare)
Investigation of alpha-phenylnorstatine and alpha-benzylnorstatine as transition state isostere motifs in the search for new BACE-1 inhibitors
2011
Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 19:1, s. 145-155
Tidskriftsartikel (refereegranskat) abstract
Inhibition of the BACE-1 protease enzyme has over the recent decade developed into a promising drug strategy for Alzheimer therapy. In this report, more than 20 new BACE-1 protease inhibitors based on alpha-phenylnorstatine, alpha-benzylnorstatine, iso-serine, and beta-alanine moieties have been prepared. The inhibitors were synthesized by applying Fmoc solid phase methodology and evaluated for their inhibitory properties. The most potent inhibitor, tert-alcohol containing (R)-12 (IC(50) = 0.19 mu M) was co-crystallized in the active site of the BACE-1 protease, furnishing a novel binding mode in which the N-terminal amine makes a hydrogen bond to one of the catalytic aspartic acids.
4.
Adeyemi, Ahmed, et al.
(författare)
Regio- and Stereoselective Synthesis of Allylic Spiroethers (Spirobenzofuranes) via an Intramolecular Mizoroki-Heck Reaction
2020
Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 85:12, s. 7648-7657
Tidskriftsartikel (refereegranskat) abstract
The palladium(0)-catalyzed intramolecular annulation of 12 1,3-disubstituted cyclopentenes, derived from (+)-vincelactam, resulted in 5-exo cyclizations which furnished a series of 2,5-dimethyl-14(3R,4'S)-2H-spiro[benzofuran-3,1'-cyclopentan]2'-en-4'-yl)-1H-pyrroles in excellent diastereoselectivities and useful isolated yields. The double bond migration process that followed the arylpalladium insertion was controlled by a fine-tuning of the reaction system, which provided regioselectivities of up to 98:2. The selective Mizoroki-Heck reaction was used as the key transformation for preparing two new spirocyclic monoprotected amino acids as single stereoisomers.
5.
Arvela, Riina K., et al.
(författare)
Highly regioselective internal heck arylation of hydroxyalkyl vinyl ethers by aryl halides in water
2007
Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 72:17, s. 6390-6396
Tidskriftsartikel (refereegranskat) abstract
Highly regioselective and fast Pd(0)-catalyzed internal α-arylation of ethylene glycol vinyl ether with aryl halides was shown to be possible in water without the need for any halide scavengers or ionic liquid additives. This presents, to our knowledge, the first case of water being utilized in the selective arylation of electron-rich olefins. Resulting α-products were hydrolyzed and isolated as corresponding acetophenones in good to excellent yields when using aryl bromides and with good to moderate yields in the case of aryl iodides. Microwave irradiation was shown to be beneficial in activation of aryl chlorides toward the internal Heck arylation. The scope of the protocol was further increased to include different hydroxyalkyl vinyl ethers, these all giving selectively only branched α-products. Finally, the active role of the hydroxy group in directing the regioselectivity toward internal arylation of electron-rich olefins, even in nonpolar toluene, was revealed.
6.
Ax, Anna, et al.
(författare)
Synthesis of a small library of non-symmetric cyclic sulfamide HIV-1 protease inhibitors
2010
Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 66:23, s. 4049-4056
Tidskriftsartikel (refereegranskat) abstract
A set of 11 non-symmetric cyclic sulfamide HIV-1 protease inhibitors were synthesized and evaluated. The use of a key microwave-assisted silver(I) oxide mediated selective mono N-benzylation reaction enabled fast and straightforward synthesis. The K-i values of the new inhibitors ranged between 0.28 mu M and >20 mu M.
7.
Borhade, Sanjay R, et al.
(författare)
Inhibition of Insulin-Regulated Aminopeptidase (IRAP) by Arylsulfonamides
2014
Ingår i: ChemistryOpen. - : Wiley. - 2191-1363. ; 3:6, s. 256-263
Tidskriftsartikel (refereegranskat) abstract
The inhibition of insulin-regulated aminopeptidase (IRAP, EC 3.4.11.3) by angiotenesin IV is known to improve memory and learning in rats. Screening 10 500 low-molecular-weight compounds in an enzyme inhibition assay with IRAP from Chinese Hamster Ovary (CHO) cells provided an arylsulfonamide (N-(3-(1H-tetrazol-5-yl)phenyl)-4-bromo-5-chlorothiophene-2-sulfonamide), comprising a tetrazole in the meta position of the aromatic ring, as a hit. Analogues of this hit were synthesized, and their inhibitory capacities were determined. A small structure-activity relationship study revealed that the sulfonamide function and the tetrazole ring are crucial for IRAP inhibition. The inhibitors exhibited a moderate inhibitory potency with an IC50=1.1±0.5 μm for the best inhibitor in the series. Further optimization of this new class of IRAP inhibitors is required to make them attractive as research tools and as potential cognitive enhancers.
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10.
Ekegren, Jenny K, et al.
(författare)
Microwave-accelerated synthesis of P1'-extended HIV-1 protease inhibitors encompassing a tertiary alcohol in the transition-state mimicking scaffold
2006
Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 49:5, s. 1828-1832
Tidskriftsartikel (refereegranskat) abstract
Two series of P1'-extended HIV-1 protease inhibitors comprising a tertiary alcohol in the transition-state mimic exhibiting Ki values ranging from 2.1 to 93 nM have been synthesized. Microwave-accelerated palladium-catalyzed cross-couplings were utilized to rapidly optimize the P1' side chain. High cellular antiviral potencies were encountered when the P1' benzyl group was elongated with a 3- or 4-pyridyl substituent (EC50 = 0.18-0.22 microM). X-ray crystallographic data were obtained for three inhibitors cocrystallized with the enzyme.
