| 1. |
- Angelin, Marcus, et al.
(författare)
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Crystallization-induced secondary selection from a tandem driven dynamic combinatorial resolution process
- 2008
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 73:9, s. 3593-3595
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Tidskriftsartikel (refereegranskat)abstract
- Crystallization-induced secondary selection from a tandem driven dynamic combinatorial library is presented. In a one-pot experiment, an initial nitroaldol equilibrium was kinetically driven by a tandem reaction resulting in a subsequent dynamic library of diastereoisomers. This library was then further driven by a phase change, resulting in amplification and isolation of a highly diastereomerically enriched and synthetically interesting isoindolinone.
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| 2. |
- Arefalk, Anna, et al.
(författare)
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Stereoselective Synthesis of 3-Aminoindan-1-ones and Subsequent Incorporation into HIV-1 Protease Inhibitors
- 2006
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Ingår i: Journal of Organic Chemistry. - 0022-3263 .- 1520-6904. ; 71:3, s. 1265-1268
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Tidskriftsartikel (refereegranskat)abstract
- A new method for the stereoselective synthesis of 3-aminoindan-1-ones from triflates of salicylic sulfinyl imines and ethylene glycol vinyl ether has been developed. The reaction sequence starts with a regioselective Heck reaction followed by stereoselective Lewis acid mediated annulation. Acidic cleavage of the sulfinamides produced pure (R)- and (S)-3-aminoindan-1-ones, which were successfully isolated and incorporated into active HIV-1 protease inhibitors.
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| 3. |
- Arvela, Riina K, et al.
(författare)
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A reassessment of the transition-metal free suzuki-type coupling methodology.
- 2005
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 70:1, s. 161-168
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Tidskriftsartikel (refereegranskat)abstract
- We present here a reassessment of our transition-metal free Suzuki-type coupling protocol. We believe that, although the reaction can be run without the need for addition of a metal catalyst, palladium contaminants down to a level of 50 ppb found in commercially available sodium carbonate are responsible for the generation of the biaryl rather than, as previously suggested, an alternative non-palladium-mediated pathway. We present a revised methodology for Suzuki couplings using ultralow palladium concentrations for use with aryl and vinyl boronic acids and discuss the effects of the purity of the boronic acid on the reaction.
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| 4. |
- Arvela, Riina K., et al.
(författare)
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Highly regioselective internal heck arylation of hydroxyalkyl vinyl ethers by aryl halides in water
- 2007
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 72:17, s. 6390-6396
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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.
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| 5. |
- Arvela, Riina K, et al.
(författare)
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Microwave-promoted Heck coupling using ultralow metal catalyst concentrations.
- 2005
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 70:5, s. 1786-1790
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Tidskriftsartikel (refereegranskat)abstract
- We show that Heck couplings can be performed in water using microwave heating and Pd catalyst concentrations as low as 500 ppb. The methodology is simple; all that is required as the catalyst is a stock solution of palladium.
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| 6. |
- Aydin, Juhanes, et al.
(författare)
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Synthesis and catalytic application of chiral 1,1'-Bi-2-naphthol- and biphenanthrol-based pincer complexes: selective allylation of sulfonimines with allyl stannane and allyl trifluoroborate.
- 2007
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 72:13, s. 4689-4697
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Tidskriftsartikel (refereegranskat)abstract
- New easily accessible 1,1'-bi-2-naphthol- (BINOL-) and biphenanthrol-based chiral pincer complex catalysts were prepared for selective (up to 85% enantiomeric excess) allylation of sulfonimines. The chiral pincer complexes were prepared by a flexible modular approach allowing an efficient tuning of the selectivity of the catalysts. By employment of the different enantiomeric forms of the catalysts, both enantiomers of the homoallylic amines could be selectively obtained. Both allyl stannanes and allyl trifluoroborates can be employed as allyl sources in the reactions. The biphenanthrol-based complexes gave higher selectivity than the substituted BINOL-based analogues, probably because of the well-shaped chiral pocket generated by employment of the biphenanthrol complexes. The enantioselective allylation of sulfonimines presented in this study has important implications for the mechanism given for the pincer complex-catalyzed allylation reactions, confirming that this process takes place without involvement of palladium(0) species.
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| 7. |
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| 8. |
- Bielawski, Marcin, et al.
(författare)
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Regiospecific One-Pot Synthesis of Diaryliodonium Tetrafluoroborates from Arylboronic Acids and Aryl Iodides
- 2008
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 73:12, s. 4602-4607
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Tidskriftsartikel (refereegranskat)abstract
- Diaryliodonium salts have recently received considerable attention as mild arylation reagents in organic synthesis. This paper describes a regiospecific, sequential one-pot synthesis of symmetrical and unsymmetrical diaryliodonium tetrafluoroborates, which are the most popular salts in metal-catalyzed arylations. The protocol is fast and high-yielding and has a large substrate scope. Furthermore, the corresponding diaryliodonium triflates can conveniently be obtained via an in situ anion exchange.
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| 9. |
- Billing, Johan, et al.
(författare)
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C2-Symmetric Macrocyclic Carbohydrate/Amino Acid Hybrids through Copper(I)-Catalyzed Formation of 1,2,3-Triazoles
- 2005
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 1520-6904 .- 0022-3263. ; 70:12, s. 4847-4850
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Tidskriftsartikel (refereegranskat)abstract
- An efficient method was developed for the preparation of macrocyclic carbohydrate/amino acid hybrids by macrocyclization with copper(I)-catalyzed 1,2,3-triazole formation. Methyl 2-amino-6-azido-3,4-di-O-benzoyl-2,6-dideoxy--D-glucopyranoside was prepared and coupled to two different N-propiolyl dipeptides (propiolyl-Tyr-Tyr-OH and propiolyl-Arg(Mtr)-Tyr-OH) to obtain bifunctional molecules carrying one azido group and one terminal alkyne. These bifunctional molecules were cyclodimerized using Cu(I)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes to form macrocycles containing two 1,2,3-triazoles. Various cyclization methods were evaluated, and the most efficient conditions were found to be CuI and N,N-diisopropylethylamine in CH3CN.
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| 10. |
- Blid, Jan, et al.
(författare)
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Lewis acid mediated asymmetric 2,3 -sigmatropic rearrangement of allylic amines. Scope and mechanistic investigation
- 2007
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 72:4, s. 1294-1300
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Tidskriftsartikel (refereegranskat)abstract
- [GRAPHIC] The first asymmetric [2,3]-sigmatropic rearrangement of achiral allylic amines has been realized by quaternization of the amines with an enantiomerically pure diazaborolidine and subsequent treatment with Et3N. The resultant homoallylic amines were obtained in good yields and excellent ee's. The observed diastereo- and enantioselectivities were rationalized by invoking a kinetically controlled process, and support for this model was obtained from an NMR spectroscopic investigation of the chiral Lewis acid-substrate complex. The structure of the Lewis acid-product complex was established by X-ray crystallographic analysis and supported the proposed mechanism.
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