63677-96-3Relevant articles and documents
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.
α′-Hydroxyenones as mechanistic probes and scope-expanding surrogates for α,β-unsaturated aldehydes in N-heterocyclic carbene-catalyzed reactions
Chiang, Pei-Chen,Rommel, Michael,Bode, Jeffrey W.
supporting information; experimental part, p. 8714 - 8718 (2009/10/23)
N-heterocyclic carbene-catalyzed reactions of α,β-unsaturatedaldehydes and a variety of electrophiles allow the facile preparation o f a diverse array of annulation products including trisubstituted cyclopentenes, γ-lactams, and bicyclic β-lactams. The substrate scope of these reactions, however, is limited by the difficulties of preparing the starting α,β-unsaturated aldehydes. We now report that α′- hydroxyenones, which can be prepared in a single convenient step from aromatic and heteroaromatic aldehydes, can serve as efficient surrogates for enals in the annulation reactions. This protocol allows the facile preparation and use of substrates bearing nitrogen heterocycles. These reagents have also allowed us to demonstrate that, in contrast to other classes of aldehydes, the formation of the Breslow intermediate from enals and N-heterocyclic carbenes is irreversible under the reaction conditions.
Catalytic amide formation with α′-hydroxyenones as acylating reagents
Chiang, Pei-Chen,Kim, Yoonjoo,Bode, Jeffrey W.
supporting information; experimental part, p. 4566 - 4568 (2010/01/06)
α′-Hydroxyenones undergo clean, catalytic amidations with amines promoted by the combination of an N-heterocyclic carbene and 1,2,4-triazole. The Royal Society of Chemistry 2009.
Copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to α′-oxy enones
Garcia, Jesus M.,Gonzalez, Alberto,Kardak, Bharat G.,Odriozola, Jose M.,Oiarbide, Mikel,Razkin, Jesus,Palomo, Claudio
supporting information; experimental part, p. 8768 - 8771 (2009/10/01)
The copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to α'-oxy enones was investigated. Cu(OTf)2, ligand, and toluene were placed in a flame-dried Schlenk tube. the resulting mixture was stirred at room temperature f
Palladium-catalyzed oxidative cyclizations: Synthesis of dihydropyranones and furanones
Reiter, Maud,Turner, Hazel,Mills-Webb, Rebecca,Gouverneur, Veronique
, p. 8478 - 8485 (2007/10/03)
A boron-mediated syn- and anti-stereoselective aldol reaction giving rise to various β-hydroxyenones was coupled to a Pd(II)-mediated oxidative cyclization to give 2,3,6-trisubstituted syn- and antidihydropyranones in good yields. The Pd(I
α′-hydroxy Enones as Achiral Templates for Lewis Acid-Catalyzed Enantioselective Diels - Alder Reactions
Palomo, Claudio,Oiarbide, Mikel,Garcia, Jesus M.,Gonzalez, Alberto,Arceo, Elena
, p. 13942 - 13943 (2007/10/03)
α′-Hydroxy enones react with dienes in the presence of (S,S)-[Cu(tBu-box)](OTf)2 or (S,S)-[Cu(tBu-box)](SbF6)2 (2 to 10 mol %) to afford the corresponding Diels?Alder adducts in high yield and selectivity. Isomeric ratios (regioselectivity, endo/exo or cis/trans) of up to >99:1 and ee values of up to >99% are obtained. Significantly, difficult dienes such as isoprene, 2,3-dimethyl butadiene and piperylene behave satisfactorily. Subsequent oxidative cleavage of the ketol in the resulting cycloadducts by treatment with cerium ammonium nitrate (CAN) yields the corresponding enantiopure carboxylic acids. Alternatively, carbonyl addition and subsequent diol cleavage with CAN produces the corresponding ketone adducts. Copyright
Benzotriazole- and 1,2,4-triazole-stabilized allylic anions: Applications in syntheses of functionalized α,β-unsaturated ketones, γ-lactones, γ-lactams, and β-substituted esters
Katritzky,Feng,Lang
, p. 706 - 714 (2007/10/03)
Deprotonated 1-(benzotriazol-1-yl)-1-ethoxy-2-hexene (7) reacted with alkyl halides, aldehydes, ketones, imines, and α,β-unsaturated esters to give exclusively the α-alkylated products 8a-c, 10a,b, 12, 14, 16, and 18a,b, respectively. Without isolation, these products were hydrolyzed under mild conditions to generate the corresponding simple or functionalized α,β-unsaturated ketenes 9a-c, 11a,b, 13, 15, 17, and 19a,b. Similar reactions with the phenyl-substituted analog 3-(benzotriazol-1-yl)-3-ethoxy-1-phenyl-1-propene (21) also gave the analogous α-products, but they were accompanied by small amounts of the γ-products in most cases. By contrast, deprotonation of the corresponding triazole derivative 29 with butyllithium followed by reactions with alkyl halides, aldehydes, ketones, or imines yielded exclusively γ-alkylated adducts 32, 34, 36, 38, 40, and 42. Intermediates 32, 34, 36, 38, 40, and 42 were readily converted into β-substituted esters 33a-c, γ-lactones 35a,b, 39, 41, and 43, and γ-lactams 37a-c on hydrolysis.
A Novel and Practical Synthetic Method of 3(2H)-Furanone Derivatives
Sakai, Takashi,Yamawaki, Akitoshi,Ito, Hiroshi,Utaka, Masanori,Takeda, Akira
, p. 1199 - 1201 (2007/10/02)
A novel convenient synthetic method of 5-aryl-2,2-dimethyl-3(2H)-furanones (aryl = C6H5, 2-CH3C6H4, 3-CH3C6H4, 4-CH3C6H4, 2-ClC6H4, 4-ClC6H4, 2,4-Cl2C6H3) is described.It involves the Claisen-Schmidt condensation (potassium hydroxide/ethanol) of aromatic
STEREOSELECTIVE SYNTHESIS OF CIS-α,β-EPOXYESTERS AND ALDEHYDES VIA DIVALENT TIN ENOLATE. A SYNTHESIS OF 2-AMINO-2-DEOXY-D-ARABINITOL
Mukaiyama, Teruaki,Yura, Takeshi,Iwasawa, Nobuharu
, p. 809 - 812 (2007/10/02)
A convenient method for the stereoselective synthesis of cis-α,β-epoxyesters and aldehydes is established according to the Sn(OTf)2 mediated cross aldol reaction between α-bromo-α'-silyloxyketone and aldehyde.The reaction is applied to the stereoselective synthesis of 2-amino-2-deoxy-D-arabinitol.
Regiocontrolled Formation of 4,5-Dihydro-3(2H)-furanones from 2-Butyne-1,4-diol Derivatives. Synthesis of Bullatenone and Geiparvarin
Saimoto, Hiroyuki,Hiyama, Tamejiro,Nozaki, Hitosi
, p. 3078 - 3087 (2007/10/02)
Two new methods for selective hydration of 1,1,4-trisubstituted 2-butyne-1,4-diols (1) to give 4,5-dihydro-3(2H)-furanone derivatives are reported.The first involves selective monoacetylation of the less hindered hydroxyl group of 1 followed by Ag(I)-cata
