584-93-0Relevant articles and documents
Silver-Promoted Fluorination Reactions of α-Bromoamides
Mizuta, Satoshi,Kitamura, Kanami,Kitagawa, Ayako,Yamaguchi, Tomoko,Ishikawa, Takeshi
supporting information, p. 5930 - 5935 (2021/02/01)
Silver-promoted C?F bond formation in α-bromoamides by using AgF under mild conditions is reported. This simple method enables access to tertiary, secondary, and primary alkyl fluorides involving biomolecular scaffolds. This transformation is applicable to primary and secondary amides and shows broad functional-group tolerance. Kinetics experiments revealed that the reaction rate increased in the order of 3°>2°>1° α-carbon atom. In addition, it was found that the acidic amide proton plays an important role in accelerating the reaction. Mechanistic studies suggested generation of an aziridinone intermediate that undergoes subsequent nucleophilic addition to form the C?F bond with stereospecificity (i.e., retention of configuration). The synthesis of sterically hindered alcohols and ethers by using AgI is also demonstrated. Examples of reactions of α-bromoamides with O nucleophiles are presented.
Enantioselective construction of tetrasubstituted stereogenic carbons through bronsted base catalyzed michael reactions: α′-hydroxy enones as key enoate equivalent
Badiola, Eider,Fiser, Bla,Gmez-Bengoa, Enrique,Mielgo, Antonia,Olaizola, Iurre,Urruzuno, Iaki,Garca, Jess M.,Odriozola, Jos M.,Razkin, Jess,Oiarbide, Mikel,Palomo, Claudio
supporting information, p. 17869 - 17881 (2015/02/19)
Catalytic and asymmetric Michael reactions constitute very powerful tools for the construction of new C-C bonds in synthesis, but most of the reports claiming high selectivity are limited to some specific combinations of nucleophile/electrophile compound types, and only few successful methods deal with the generation of all-carbon quaternary stereocenters. A contribution to solve this gap is presented here based on chiral bifunctional Bronsted base (BB) catalysis and the use of α′-oxy enones as enabling Michael acceptors with ambivalent H-bond acceptor/donor character, a yet unreported design element for bidentate enoate equivalents. It is found that the Michael addition of a range of enolizable carbonyl compounds that have previously demonstrated challenging (i.e., α-substituted 2-oxindoles, cyanoesters, oxazolones, thiazolones, and azlactones) to α′-oxy enones can afford the corresponding tetrasubstituted carbon stereocenters in high diastereo- and enantioselectivity in the presence of standard BB catalysts. Experiments show that the α′-oxy ketone moiety plays a key role in the above realizations, as parallel reactions under identical conditions but using the parent α,β-unsaturated ketones or esters instead proceed sluggish and/or with poor stereoselectivity. A series of trivial chemical manipulations of the ketol moiety in adducts can produce the corresponding carboxy, aldehyde, and ketone compounds under very mild conditions, giving access to a variety of enantioenriched densely functionalized building blocks containing a fully substituted carbon stereocenter. A computational investigation to rationalize the mode of substrate activation and the reaction stereochemistry is also provided, and the proposed models are compared with related systems in the literature.
Mesoionic 5-alkyl-1,3-dithiolium-4-thiolates: Synthesis and brine shrimp toxicity
De Almeida, Paulo Afonso,Da Silva, Tania Maria Sarmento,Echevarria, Aurea
, p. 593 - 600 (2007/10/03)
A series of twelve 1,3-dithiolium-4-thiolate mesoionic compounds were synthesized and characterized. The synthetical approach starting from α-bromoalkanoic acids to obtain the corresponding 2-N-morpholino-dithiocarbamoyl-carboxylic acids that by on-pot reaction with carbon disulfide and acetic anhydride in triethylamine formed not isolate intermediates, 1,3-dithiolium-4-olates. After, the 2-N-morpholino-5-alkyl-1,3-dithiolium-4-thiolates were obtained by retro 1,3-dipolar addition reactions. The alkyl moiety linked to C-5 of heterocyclic ring permitted the increase of the hydrophobic character and this effect was evaluated on Artemia salina lethality. The results indicated a bell-shaped relationship between the number of carbon of side chain in mesoionic derivatives and LD50 in brine shrimp toxicity assays.