35155-66-9Relevant academic research and scientific papers
C-O Bond Activation as a Strategy in Palladium-Catalyzed Cross-Coupling
Becica, Joseph,Leitch, David C.
, p. 641 - 646 (2020/12/14)
The activation of strong C-O bonds in cross-coupling catalysis can open up new oxygenate-based feedstocks and building blocks for complex-molecule synthesis. Although Ni catalysis has been the major focus for cross-coupling of carboxylate-based electrophiles, we recently demonstrated that palladium catalyzes not only difficult C-O oxidative additions but also Suzuki-Type cross-couplings of alkenyl carboxylates under mild conditions. We propose that, depending on the reaction conditions, either a typical Pd(0)/(II) mechanism or a redox-neutral Pd(II)-only mechanism can operate. In the latter pathway, C-C bond formation occurs through carbopalladation of the alkene, and C-O cleavage by β-carboxyl elimination. 1 Introduction 2 A Mechanistic Challenge: Activating Strong C-O Bonds 3 Exploiting Vinylogy for C-Cl and C-O Oxidative Additions 4 An Alternative Mechanism for Efficient Cross-Coupling Catalysis 5 Conclusions and Outlook.
Formation and Reactivity of Triplet Vinylnitrenes as a Function of Ring Size
Gatlin, Devonna M.,Karney, William L.,Abe, Manabu,Ault, Bruce S.,Gudmundsdottir, Anna D.
, p. 9215 - 9225 (2019/08/12)
The photoreactivity of cyclic vinyl azides 1 (3-azido-2-methyl-cyclopenten-1-one) and 2 (3-azido-2-methyl-2-cyclohexen-1-one), which have five- and six-membered rings, respectively, was characterized at cryogenic temperature with electron paramagnetic resonance (EPR), IR, and UV spectroscopy. EPR spectroscopy revealed that irradiating (λ > 250 nm) vinyl azides 1 and 2 in 2-methyltetrahydrofuran at 10 K resulted in the corresponding triplet vinylnitrenes 31N (D/hc = 0.611 cm-1 and E/hc = 0.011 cm-1) and 32N (D/hc = 0.607 cm-1 and E/hc = 0.006 cm-1), which are thermally stable at cryogenic temperature. Irradiation of vinyl azides 1 (310 nm light-emitting diode at 12 K) and 2 (xenon arc lamp through a 310-350 nm filter at 8 K) in argon matrices showed that in competition with intersystem crossing to form vinylnitrenes 31N and 32N, vinyl azide 1 formed a small amount of ketenimine 3, whereas vinyl azide 2 formed significant amounts of azirine 7 and ketenimine 6. Thus, vinyl azide 1 undergoes intersystem crossing more efficiently than vinyl azide 2. Similarly, vinylnitrene 31N is much more photoreactive than vinylnitrene 32N. Quantum chemical calculations were used to support the mechanisms for forming vinylnitrenes 31N and 32N and their reactivity.
Highly enantioselective and regioselective carbonyl reduction of cyclic α,β-unsaturated ketones using TarB-N02 and sodium borohydride
Kim, Jinsoo,Bruning, John,Park, Kevin E.,Lee, David J.,Singaram, Bakthan
supporting information; experimental part, p. 4358 - 4361 (2009/12/24)
Asymmetric 1,2-reduction of α,β-unsaturated ketones using TarB-NO2 and NaBH4 Is reported. Simple cycloalkenones give products In low enantiomeric excess. However, cycloalkenones with a-substituents, such as halides, alkyl, and aryl, have been enantioselectively reduced with this system to yield chiral allylic alcohols In enantiomeric excess up to 99%. The starting materials for TarB-N02 are inexpensive, and the boronlc acid can be easily recovered In high yield by a simple acid extraction.
THE REACTION OF DIALKYLTRICHLOROMETHYLPHOSPHINES WITH METHYL ISOCYANATE AND WITH SATURATED AND α,β-UNSATURATED CARBONYL COMPOUNDS
Majewski, Piotr
, p. 59 - 66 (2007/10/02)
Diethyltrichloromethylphosphine (4a) reacts with methyl isocyanate (6e) and with nonenolizable saturated aldehydes, 6b-c, to produce 1,2-λ5-oxaphosphetanes, 7b-e, whereas with enolizable saturated ketones, 6f,g, it gives mixtures of cycloaddition products, 7f,g, and vinyl chlorides, 14f,g.By treatment with 4a, 1,3-diketones 6h-j are exclusively transformed into vinyl chlorides, 14h-j. α,β-Unsaturated aldehydes, 6k,l, react with 4a to afford phosphine oxides 17k,l.The crucial role of the oxaphosphetane type intermediates, 15k,l, in the formation of 17k,l has been demonstrated. Key words: Diethyltrichloromethylphosphine; P-chlorodiethyldichloromethylenephosphorane; 1,2,λ5-oxaphosphetane; saturated and α,β-unsaturated carbonyl compounds; diethyl-(1,1-dichloroalkyl)phosphine oxides.
VILSMEIER REAGENTS: PREPARATION OF β-HALO-α,β-UNSATURATED KETONES
Mewshaw, Richard E.
, p. 3753 - 3756 (2007/10/02)
A new method for the preparation of β-chloro and β-bromo-α,β-unsaturated ketones from β-diketones is described.Utilizing Vilsmeier reagents (prepared from N,N-dimethylformamide and oxalyl chloride or oxalyl bromide) β-halo-α,β-unsaturated ketones are isolated in excellent yields.
Transformation of β-diketones to β-chloro-α,β-unsaturated ketones induced by lithium hydride and phenyl dichlorophosphate
Liu, Hsing-Jang,Lamoureux, Guy V.,Llinas-Brunet, Montse
, p. 520 - 522 (2007/10/02)
The conversion of β-diketones to the corresponding β-chloro-α,β-unsaturated ketones is facilitated by using lithium hydride as a base and phenyl dichlorophosphate as an activating agent.
Synthesis of β-chloro, β-bromo, and β-iodo α,β-unsaturated ketones
Piers, Edward,Grierson, John R.,Lau, Cheuk Kun,Nagakura, Isao
, p. 210 - 223 (2007/10/02)
A new, efficient method for the preparation of β-chloro, β-bromo, and β-iodo α,β-unsaturated ketones is described.The method involves the reaction of β-diketones or α-hydroxymethylenecycloalkanones with triphenylphosphine dihalides in the presence of trie
