15121-79-6Relevant academic research and scientific papers
Enantioselective One-pot Synthesis of 3-Azabicyclo[3.1.0]hexanes via Allylic Substitution and Oxidative Cyclization
Chaki, Bijan Mohon,Takenaka, Kazuhiro,Zhu, Linpeng,Tsujihara, Tetsuya,Takizawa, Shinobu,Sasai, Hiroaki
, p. 1537 - 1547 (2020)
An enantioselective one-pot synthesis of 3-azabicyclo[3.1.0]hexanes from allyl carbonates and propargyl amines is reported. An amine catalyst promoted the allylic substitution to form intermediary N-allyl propargylamines, which underwent enantioselective Pd(II)/Pd(IV)-mediated oxidative cyclization in situ. The chiral ligand (P,R,R)-i-Pr-SPRIX is crucial to the cyclization, producing the desired bicyclic compounds in up to 92% yield and 90% ee. (Figure presented.).
N-Heterocyclic Carbene Catalyzed (5+1) Annulations Exploiting a Vinyl Dianion Synthon Strategy
Nguyen, Xuan B.,Nakano, Yuji,Duggan, Nisharnthi M.,Scott, Lydia,Breugst, Martin,Lupton, David W.
supporting information, p. 11483 - 11490 (2019/07/18)
Direct polarity inversion of conjugate acceptors provides a valuable entry to homoenolates. N-heterocyclic carbene (NHC) catalyzed reactions, in which β-unsubstituted conjugate acceptors undergo homoenolate formation and C?C bond formation twice, have been developed. Specifically, the all-carbon (5+1) annulations give a range of mono- and bicyclic cyclohexanones (31 examples). In the first family of annulations, β-unsubstituted acrylates tethered to a divinyl ketone undergo cycloisomerization, providing hexahydroindenes and tetralins. In the second, partially untethered substrates undergo an intermolecular (5+1) annulation involving dimerization followed by cycloisomerization. While enantioselectivity was not possible with the former, the latter proved viable, allowing cyclohexanones to be produced with high levels of enantiopurity (most >95:5 e.r.) and exclusive diastereoselectivity (>20:1 d.r.). Derivatizations and mechanistic studies are also reported.
Simple organocatalysts in multi-step reactions: An efficient one-pot Morita-Baylis-Hillman-type α-hydroxymethylation of vinyl ketones followed by the convenient, temperature-controlled one-pot etherification using alcohols
Mantel, Marvin,Guder, Marian,Pietruszka, J?rg
, p. 5442 - 5450 (2018/05/25)
1,4-Diazabicyclo[2.2.2]octane (DABCO) was utilized as versatile catalyst in a one-pot synthesis: First, for the preparation of alcoholic formaldehyde solutions from para-formaldehyde catalysed by using low loadings of inexpensive DABCO. Second, for the fast α-hydroxymethylation of alkylic and aromatic vinyl ketones in high yields. In a third step, the same catalyst can be used for an optional, temperature controlled in situ etherification of the Morita-Baylis-Hillman product with various alcohols on a multi-gram scale in moderate to good overall yields and high purities. Furthermore, an application of the ether in the enantioselective synthesis of a common building block for total synthesis is shown, thus providing a gram-scale access from inexpensive bulk chemicals.
Concise synthesis of α-(hydroxymethyl) alkyl and aryl vinyl ketones
Kraem, Jihene Ben,Amri, Hassen
, p. 110 - 117 (2012/10/30)
2,4-Diketoesters 2 have first been reported as starting materials for the synthesis of a new class of α-hydroxymethyl-α,β-unsaturated ketones 3. Thus, under heterogeneous liquid-liquid medium in the presence of concentrated aqueous potassium carbonate as a base, both aliphatic and aromatic 2,4-dioxoalkanoates 2 react with aqueous formaldehyde to afford the corresponding ketones 3 in fair to good yields. Copyright Taylor & Francis Group, LLC.
A Synthetic and Computational Investigation into the Direct Synthesis of α -Hydroxymethylated Enones from β-keto Phosphonates
Ryan, Sarah J.,Thompson, Christopher D.,Lupton, David W.
experimental part, p. 720 - 727 (2010/02/16)
The synthesis of a range of -hydroxymethylated enones has been achieved using the Villiras modification of the HornerWadsworthEmmons (HWE) reaction. Scope, limitations, and mechanistic aspects of this reaction were investigated using a combination of synthetic and computational studies. These investigations support a SchlosserCorey type reaction mechanism that is balanced between two pathways with the outcome influenced by the steric environment of the substrate. CSIRO 2009.
Facile 1,3-diaza-Claisen rearrangements of tertiary allylic amines bearing an electron-deficient alkene
Aranha, Rachel M.,Bowser, Amy M.,Madalengoitia, Jose S.
supporting information; experimental part, p. 575 - 578 (2009/07/18)
(Chemical Equation Presented) Tertiary allylic amines with an electron-deficient alkene react with isocyanates and isothiocyanates to give highly substituted ureas and thioureas arising from formal 1,3-diaza-Claisen rearrangements. Isocyanates and isothiocyanates with strong electron-withdrawing groups are more reactive. Similarly, the data suggest that a stronger electron-withdrawing substituent on the alkene favors a faster reaction, but this may be offset by sterlcs in the cyclic transition state.
A direct synthesis of α-(hydroxymethyl) and α-alkyl-vinyl alkyl ketones
Kra?em, Jihène Ben,Ayed, Ta?cir Ben,Amri, Hassen
, p. 7077 - 7079 (2007/10/03)
Reaction of 2,4-diketoesters 3a-c with aqueous formaldehyde using potassium carbonate solution as base affords the corresponding α-methylene-β-hydroxyalkanones 4a-c which provide a route to α,β-unsaturated alkyl ketones 6a-e via coupling of α-acetoxymethy
The Aldol Reaction under High-Intensity Ultrasound: A Novel Approach to an Old Reaction
Cravotto, Giancarlo,Demetri, Alberto,Nano, Gian Mario,Palmisano, Giovanni,Penoni, Andrea,Tagliapietra, Silvia
, p. 4438 - 4444 (2007/10/03)
We have employed high-intensity ultrasound (HIU) to reinvestigate the aldol reaction (AR) in water. A number of aldols that under usual conditions would undergo elimination were isolated in acceptable to good yields. Within 15-30 min, acetophenone reacted with non-enolizable aldehydes to afford the aldol exclusively, while under conventional conditions (stirring or heating under reflux) the same compounds either failed to react or gave, after several hours, the enone, often in complex product mixtures. A library of polyols was obtained starting from a series of acetophenones and excess formaldehyde. Benzaldehyde reacted with a series of 1,3-dicarbonyl compounds to afford the corresponding bis(benzylidene) adducts. The results proved to be highly reproducible because the relevant sonochemical parameters were rigorously controlled. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
