19860-71-0Relevant academic research and scientific papers
New preparation of stereodefined α,α-unsaturated ketones by carbomagnesiation of α-allenyl ketones
Chinkov, Nicka,Morlender-Vais, Natalia,Marek, Ilan
, p. 6009 - 6010 (2002)
The addition of several alkylmagnesium halides to an α-allenyl ketone leads to the corresponding α,β-unsaturated ketones as single geometrical isomers. A π-chelation between the metal and the unsaturation is proposed to explain the steric outcome of this reaction.
Continuous flow synthesis of ketones from carbon dioxide and organolithium or grignard reagents
Wu, Jie,Yang, Xiaoqing,He, Zhi,Mao, Xianwen,Hatton, T. Alan,Jamison, Timothy F.
supporting information, p. 8416 - 8420 (2014/08/18)
We describe an efficient continuous flow synthesis of ketones from CO 2 and organolithium or Grignard reagents that exhibits significant advantages over conventional batch conditions in suppressing undesired symmetric ketone and tertiary alcohol byproducts. We observed an unprecedented solvent-dependence of the organolithium reactivity, the key factor in governing selectivity during the flow process. A facile, telescoped three-step-one-flow process for the preparation of ketones in a modular fashion through the in-line generation of organometallic reagents is also established.
Domino gold-catalyzed rearrangement and fluorination of propargyl acetates
De Haro, Teresa,Nevado, Cristina
supporting information; scheme or table, p. 248 - 249 (2011/02/23)
A combination of IPrAuNTf2 as catalyst in the presence of Selectfluor has been successfully used for the high yielding synthesis of α-fluoroenones via 1,3-acyloxy rearrangement of propargyl acetates followed by Csp2-F bond formation,
Triazole-gold-promoted, effective synthesis of enones from propargylic esters and alcohols: A catalyst offering chemoselectivity, acidity and ligand economy
Wang, Dawei,Zhang, Yanwei,Harris, Alexandria,Gautam, Lekh Nath S.,Chen, Yunfeng,Shi, Xiaodong
supporting information; experimental part, p. 2584 - 2588 (2011/12/01)
The air, moisture and thermally stable 1,2,3-triazole coordinated gold(I) complexes (TA-Au) were revealed as the effective catalysts in promoting propargylic ester rearrangement and sequential allene hydration, giving the enones with excellent yields (up to 97% yields, 0.2% loading). The catalysts could also catalyze the more challenging Meyer-Schuster rearrangement (0.5% loading, up to 98% yields). The reported reaction confirmed TA-Au as a chemoselective catalyst in promoting alkyne activation with high efficiency and improved ligand economy. Copyright
4,5 Dihydro-(1H)-Pyrazole Derivatives as Cannabinoid CB1 Receptor Modulators
-
Page/Page column 12, (2009/01/24)
The invention is directed to 4,5-dihydro-(1H)-pyrazole (pyrazoline) derivatives as cannabinoid CB1 receptor modulators, to pharmaceutical compositions comprising these compounds, to methods for their syntheses, to methods for preparing novel intermediates useful for their syntheses, and to methods for preparing compositions. The invention also relates to the uses of compounds and compositions administered to patients to achieve a therapeutic effect in multiple sclerosis, traumatic brain injury, pain including chronic pain, neuropathic pain, acute pain and inflammatory pain, osteoporosis, appetite disorders, epilepsy, Alzheimer's disease, Tourette's syndrome, cerebral ischaemia, emesis, nausea, and gastrointestinal disorders. Compounds of the present disclosure are directed to formula (I): wherein the substituents have the definitions given in the specification.
Gold-catalyzed efficient formation of α,β-unsaturated ketones from propargylic acetates
Yu, Meng,Li, Guotao,Wang, Shaozhong,Zhang, Liming
, p. 871 - 875 (2008/03/27)
An efficient gold-catalyzed method for the preparation of α,β-unsaturated ketones from propargylic acetates has been developed. Under mild reaction conditions, β-monosubstituted enones were formed mostly with excellent E-selectivity. β,β-Disubstituted enones can be prepared from propargylic acetates derived from ketones. The high efficiency and mild nature of this reaction render it a viable alternative for the synthesis of α,β-unsaturated ketones.
The regioselective 1,4-addition reaction of alkenylboronic acids to α,β,α′,β′-unsaturated ketones
Hara, Shoji,Shudoh, Hisashi,Ishimura, Shigeyuki,Suzuki, Akira
, p. 2403 - 2408 (2007/10/03)
The effect of substituents on the double bond of α,β-unsaturated ketones for the 1,4-addition reaction rate of alkenylboronic acids induced by cyanuric fluoride was studied in detail. When the steric hindrance around the β-carbon of the unsaturated ketones increased, the 1,4-addition reaction rate significantly decreased. An alkyl substituent on the α-carbon was also found to significantly affect the 1,4-addition reaction. From these results, unsymmetric α,β,α′,β′unsaturated ketones (10a-f) were designed for the regioselective 1,4-addition reaction with alkenylboronic acids (4a-j). Since they have substituents to disturb the 1,4-addition reaction on only one double bond, the alkenylboronic acids reacted with them from only one side to selectively provide γ,δ,α′,β′-unsaturated ketones (11a-q). Further transformations of the resulting γ,δ,α′,β′-unsaturated ketones were also performed.
Carbonyl transposition on organoselenium compounds
Comasseto, Joao V.,Lo, Wai L.,Petragnani, Nicola
, p. 7445 - 7460 (2007/10/03)
Carbonyl conjugated vinylic selenides undergo 1,3 and 1,5-carbonyl transposition sequences through organometallic reagents addition reactions followed by acid hydrolysis.
A Stereoselective Synthesis of (E)-α,β-Unsaturated Ketones Involving the Reactions of Organocerium Reagents with Secondary β-Enamino Ketones
Bartoli, Giuseppe,Marcantoni, Enrico,Petrini, Marino,Sambri, Letizia
, p. 913 - 918 (2007/10/03)
Stereoselective construction of trisubstituted alkenes has wide applicability to the synthesis of many natural products.Specifically, β-disubstituted enones are important functionalized trisubstituted alkene targets.The reaction of organocerium reagents with secondary β-enamino ketones affords β-disubstituted α,β-unsaturated ketones in fairly good yields.This process shows considerable stereoselectivity, and α,β-unsaturated ketones of (E) configuration are predominantly observed.Organolithium-derived cerium reagents display better stereoselectivity than organomagnesium-based ones.The mechanism of the reaction varies with nitrogen substitution: N-phenyl groups give 1,2-addition products, whereas substitution products are observed with N-alkyl groups.When organocerium reagents were used with β-enamino ketones bearing secondary alkyl groups at the nitrogen atom, a lack of reactivity was observed. - Keywords: assymetric substitution; cerium reagents; enamino ketones; regioselectivity; synthetic methods
172. β-Cleavage of Bis(homoallylic) Potassium Alkoxides. Two-Step Preparation of Propenyl Ketones from Carboxylic Esters. Synthesis of ar-Turmerone, α-Damascone, β-Damascone, and β-Damascenone
Snowden, Roger L.,Linder, Simon M.,Muller, Bernard L.,Schulte, Karl H.
, p. 1858 - 1878 (2007/10/02)
The transformation of 36 bis(homoallylic) alcohols VII to alkenones IX and X via β-cleavage of their potassium alkoxides VIIa in HMPA has been investigated (cf.Scheme 2).These studies have established an order of β-cleavage for 2-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1,1-dimethyl-2-propenyl, and benzyl groups in alkoxides 49a-56a and have allowed a comparison between the β-cleavage reaction and the oxy-Cope rearrangement in alkoxides 74a-83a.As illustrative synthetic applications, a two-step preparation of propenyl ketones 15-42 from carboxylic esters is described, together with syntheses of ar-turmerone (48), α-damascone ((E)-71), β-damascone ((E)-109), and β-damascenone ((E)-111).
