- Decarboxylative Conjunctive Cross-coupling of Vinyl Boronic Esters using Metallaphotoredox Catalysis
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The synthesis of complex alkyl boronic esters through conjunctive cross-coupling of vinyl boronic esters with carboxylic acids and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and involves an unprecedented decarboxylative radical addition/cross-coupling cascade of vinyl boronic esters. Excellent functional-group tolerance is displayed, and application of a range of carboxylic acids, including secondary α-amino acids, and aryl iodides provides efficient access to highly functionalized alkyl boronic esters. The decarboxylative conjunctive cross-coupling was also applied to the synthesis of sedum alkaloids.
- Aggarwal, Varinder K.,Duong, Vincent K.,Mega, Riccardo S.,Noble, Adam
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p. 4375 - 4379
(2020/02/11)
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- A rapid access to (±)-sedamine and some original N -benzyl unsaturated analogues
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Reduction of N-alkyl-2-(2-hydroxy-2-phenylethyl)pyridinium salts using excess of sodium triacetoxyborohydride afforded exclusively the corresponding tetrahydropyridine derivative bearing a piperidine ring with a double bond in the 3,4-position. Furthermore, under these conditions, syn-1,3-amino alcohols were obtained in good yield and diastereoselectivity. Georg Thieme Verlag Stuttgart · New York.
- Boussonniere, Anne,Ranaivondrambola, Tsiresy,Lebreton, Jacques,Mathe-Allainmat, Monique
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experimental part
p. 2456 - 2462
(2010/09/04)
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- Studies on the Eschenmoser coupling reaction and insights on its mechanism. Application in the synthesis of Norallosedamine and other alkaloids
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The conditions of the Eschenmoser coupling reaction were studied. The formation of the α-thioiminium ion was achieved faster in the presence of an additive (NaI) and dry chloroform as the preferred solvent. The developed conditions were used for the second part of the reaction (the sulfur extrusion itself). The present protocol avoids the formation of byproducts, which were previously described as a major drawback to be overcome. Electrospray ionization tandem mass spectrometry was used to characterize some aspects (intermediates) of the first step of the reaction mechanism. Some reduction conditions were properly tested and the selected conditions were applied to the synthesis of the natural alkaloid Norallosedamine and other derivatives.
- Neto, Brenno A.D.,Lapis, Alexandre A.M.,Bernd, Alinne B.,Russowsky, Dennis
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experimental part
p. 2484 - 2496
(2009/08/07)
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- Diastereoselective, one-pot synthesis of γ-amino alcohols from ketimines
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Deprotonation of ketimines with lithium diisopropyl amide, followed by reaction with aldehydes and subsequent reduction with aluminium hydrides gave γ-amino alcohols with moderate to good syn selectivity. The scope and limitations of this preparative meth
- Veenstra,Kinderman
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p. 1109 - 1112
(2007/10/03)
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- Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed amidoalkylation of silylenolethers. Stereocontrolled syntheses of (+/-)-sedamine and (+/-)-norsedamine
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Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed addition of 1-trimethylsilyloxy-1-phenylethene to N-ethoxycarbonyl- and N-tert-butoxycarbonyl-2-ethoxypiperidines (3a and 3b, respectively) afforded the corresponding ketocarbamates 4a and 4b, in excellent yields. Stereoselective conversion to (±)-norsedamine (7) and (±)-sedamine (8) is described.
- Pilli,Dias
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p. 2213 - 2229
(2007/10/02)
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- Nitrone Cycloadditions: Synthesis of (+/-)-Andrachamine
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The usefulness of the cycloaddition of alkenes to 2-alkyl-2,3,4,5-tetrahydropyridine oxides for the preparation of trans-2,6-dialkylpiperidines is confirmed by a stereoselective synthesis of (+/-)-andrachamine.Peroxy acid oxidation of 9-oxa-1-azabicyclononanes does not lead regioselectively to the corresponding 2-alkyl-2,3,4,5-tetrahydropyridine oxide, as had previously been claimed.
- Carruthers, William,Coggins, Peter,Weston, John B.
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p. 2323 - 2327
(2007/10/02)
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