18303-03-2Relevant academic research and scientific papers
A novel highly regio- and diastereoselective haloamination of alkenes catalyzed by divalent palladium
Lei, Aiwen,Lu, Xiyan,Liu, Guosheng
, p. 1785 - 1788 (2004)
From the readily available allylic alcohols or allylic amines, a novel Pd(II)-CuCl2-catalyzed haloamination reaction of alkenes with high chemo-, regio-, and diastereo-selectivity was developed. The reaction proceeds through trans-aminopalladat
DirectN-glycosylation of tosyl and nosyl carbamates with trichloroacetimidate donors
Khanam, Ariza,Mandal, Pintu Kumar
supporting information, p. 15386 - 15391 (2021/09/07)
Under catalyst and additive-free conditions, a convenient and highly efficient eco-friendly method for the stereoselective synthesis ofN-glycofuranosyl and glycofuranosyl sulfonamides has been developed. The two-component reaction of glycofuranosyl trichloroacetimidates with a wide range of tosyl and nosyl carbamate acceptors having varying pKa-values including non-sugar-, and sugar-derived carbamates as well as amino acid-derived carbamates, proceeded smoothly with good yield and β-stereoselectivity. In addition, the selective deprotection ofN-carbamates andN-sulfonyl groups of theN-glycoside functioning as orthogonal protective groups was performed for further functionalization of theN-glycosides.
Intramolecular Aminoazidation of Unactivated Terminal Alkenes by Palladium-Catalyzed Reactions with Hydrogen Peroxide as the Oxidant
Beccalli, Egle M.,Broggini, Gianluigi,Foschi, Francesca,Lo Presti, Leonardo,Loro, Camilla,Oble, Julie,Poli, Giovanni,Sala, Roberto
supporting information, (2020/02/28)
The palladium-catalyzed aminoazidation of aminoalkenes yielding azidomethyl-substituted nitrogen-containing heterocycles was developed. The procedure requires oxidative conditions and occurs at room temperature in the presence of hydrogen peroxide and NaN3 as the azide source. These conditions provide selective exo-cyclization/azidation of the carbon-carbon double bond, furnishing a versatile approach toward five-, six-, and seven-membered heterocyclic rings.
Self-promoted and stereospecific formation of N-glycosides
Nielsen, Michael Martin,Ma?a, Patrycja,Baldursson, Eirikur Pórir,Pedersen, Christian Marcus
, p. 5299 - 5307 (2019/05/29)
A stereoselective and self-promoted glycosylation for the synthesis of various N-glycosides and glycosyl sulfonamides from trichloroacetimidates is presented. No additional catalysts or promoters are needed in what is essentially a two-component reaction. When α-glucosyl trichloroacetimidates are employed, the reaction resulted in the stereospecific formation of the corresponding β-N-glucosides in high yields at ambient conditions. On the other hand, when equatorial glucosyl donors were used, the stereospecificity decreased and resulted in a mixture of anomers. By NMR-studies, it was concluded that this decrease in stereospecificity was due to an, until now, unpresented anomerization of the trichloroacetimidate under the very mildly acidic conditions. The mechanism and kinetics of the glycosylations have been studied by NMR-experiments, which gave an insight into the activation of trichloroacetimidates, suggesting an SNi-like mechanism involving ion pairs. The scope of glycosyl donors and sulfonamides was found to be very broad including popular N-protective groups and common glycosyl donors of various reactivity. Peracetylated GlcNAc trichloroacetimidate could be used without the need for any promotors or additives and a tyrosine side chain was glycosylated as an N-glycosyl carbamate. The N-carbamates and the N-sulfonyl groups functioned as orthogonal protective groups of the N-glycoside and hence allowed further N-functionalization without risking mutarotation of the N-glycoside. The N-glycosylation was also performed on a gram scale, without a drop in stereoselectivity nor yield.
(Diacyloxyiodo)benzenes-Driven Palladium-Catalyzed Cyclizations of Unsaturated N-Sulfonylamides: Opportunities of Path Selection
Borelli, Tea,Brenna, Stefano,Broggini, Gianluigi,Oble, Julie,Poli, Giovanni
supporting information, p. 623 - 628 (2017/02/23)
A study of the palladium(II)-catalyzed cyclization of unsaturated N-sulfonylamides was undertaken, using (diacyloxyiodo)benzenes as terminal oxidizing agents. Different reactivities were observed as a function of the nature of the unsaturation (terminal vs. internal), or of the hypervalent iodine compound used (diacetoxyiodobenzene vs. bistrifluoroacetoxyiodobenzene). Proper parameter selection allows the direction of the cyclization to be chosen towards either a global aminoacetoxylation, an allylic amination via aminopalladation, or an allylic amination via allylic C–H activation. (Figure presented.).
An unexpected Bromolactamization of Olefinic Amides Using a Three-Component Co-catalyst System
Cheng, Yi An,Yu, Wesley Zongrong,Yeung, Ying-Yeung
, p. 545 - 552 (2016/01/25)
Reaction between (N,N-dimethylamino)pyridine and isocyanate unexpectedly produced a three-component mixture. By using this mixture as an unprecedented three-component catalyst system, a facile and selective bromolactamization of olefinic amides has been developed. The protocol confers enhanced selectivity of N- over O-cyclization, leading to the formation of a structurally diverse range of lactams including both small and medium ring sizes.
Rapid and straightforward transesterification of sulfonyl carbamates
Isaksson, Rebecka,Kumpi?a, Ilze,Larhed, Mats,Wannberg, Johan
, p. 1476 - 1478 (2016/03/12)
A fast and convenient method for the alkoxy exchange of sulfonyl carbamates by simply heating in a chosen alkyl alcohol is described. No catalysts or additives are required. Microwave heating at 100-120 °C for 20-60 min resulted in good to excellent yields (53-93%) of alkyl (arylsulfonyl)carbamates where the alkyl part originates from the alcohol solvent. The developed protocol was applied to the synthesis of an angiotensin II type 2 receptor (AT2R) ligand.
Dormant versus evolving aminopalladated intermediates: Toward a unified mechanistic scenario in PdII-catalyzed aminations
Rajabi, Jamshid,Lorion, Melanie M.,Ly, Vu Linh,Liron, Frederic,Oble, Julie,Prestat, Guillaume,Poli, Giovanni
supporting information, p. 1539 - 1546 (2014/03/21)
PdII-catalyzed alkene aminopalladation and allylic Ci￡H activation are two competing reaction sequences sharing the same reaction conditions. This study aimed at understanding the factors that bias one or the other path in the intramolecular oxidative cyclization of two types of N-tosyl amidoalkenes. The results obtained are in accord with the initial generation of a high-energy cyclic (5- or 6-membered) aminopalladated intermediate. However, this latter species can evolve only if the following specific conditions are met: the availability of distocyclic β-H elimination pathway, the presence of a strong terminal oxidant, or the availability of a carbopalladation pathway. Conversely, the cyclic alkylpalladium complex is only a latent species in equilibrium with the initial substrate and cannot evolve. Such a reactivity hurdle leaves the way open for alternative reactivities such as allylic Ci￡H activation of the olefinic substrate to generate a η3-allyl complex followed by its interception by the nitrogen nucleophile, [3,3]-sigmatropic rearrangement, or decomposition. This study proposes a unifying mechanistic picture that connects these competing mechanisms. Asleep or awake? Unsaturated N nucleophiles react through two competing pathways under PdII catalysis: Ci￡H allylic activation and aminopalladation. New data are in accord with the initial generation of a high-energy cyclic aminopalladated intermediate (API) that can either evolve along different pathways such as β-H elimination, oxidation, or carbopalladation, or lay dormant, the latter leading to alternative types of reactivity, such as allylic Ci￡H activation or [3,3]-sigmatropic rearrangement, gaining the upper hand (see scheme; Ts=p-toluenesulfonyl). Copyright
A palladium-catalyzed aminoalkynylation strategy towards bicyclic heterocycles: Synthesis of (±)-trachelanthamidine
Nicolai, Stefano,Piemontesi, Cyril,Waser, Jerome
supporting information; experimental part, p. 4680 - 4683 (2011/06/23)
Sweet cyclizations: The synthesis of pyrrolizidines and indolizidines has been achieved. Olefins were subjected to an intramolecular palladium-catalyzed aminoalkynylation with the hypervalent iodine reagent TIPS-EBX. After removal of the protecting group, a two-step cyclization sequence and subsequent reduction led to the natural product (±)-trachelanthamidine (see scheme; TIPS-EBX=triisopropylsilyl ethynylbenziodoxolone).
Gold(I)-catalyzed highly regio- and stereoselective decarboxylative amination of allylic N-tosylcarbamates via base-induced aza-Claisen rearrangement in water
Xing, Dong,Yang, Dan
supporting information; experimental part, p. 1068 - 1071 (2010/06/13)
(Figure Presented)A gold(l)-catalyzed decarboxylative animation of allylic N-tosylcarbamates via base-induced aza-Claisen rearrangement has been developed. A variety of substituted W-tosyl allylic amines were obtained In good yield, excellent regloselectlvity, and high to excellent stereoselectivity. This transformation could be performed either in H2O or In one pot directly from allylic alcohols and therefore represents an efficient and environmentally benign protocol for the synthesis of N-tosyl allylic amines.
