14296-15-2Relevant academic research and scientific papers
Regioselective Silylations of Propargyl and Allyl Pivalates through Ca-Promoted Reductive C(sp3)-O Bond Cleavage
Zhang, Tianyuan,Zheng, Suhua,Kobayashi, Taro,Maekawa, Hirofumi
supporting information, p. 7129 - 7133 (2021/09/18)
A practical protocol for the regioselective preparation of 3-phenylpropargylsilanes and 3-phenylallylsilanes in yields of 36-77 and 48-86%, respectively, from readily accessible 3-phenylpropargyl and 1-phenylallyl pivalates was developed through reductive C(sp3)-O bond cleavage. This method represents the first example of the direct application of vastly abundant calcium granules to a reductive coupling reaction. A broad range of propargylsilanes and allylsilanes are simply prepared using easy-to-handle pivalates and chlorotrimethylsilane under mild catalyst-free and additive-free conditions.
Pyridinyl Amide Ion Pairs as Lewis Base Organocatalysts
Amp?ler, Torsten,Helberg, Julian,Zipse, Hendrik
supporting information, p. 5390 - 5402 (2020/05/19)
Pyridinyl amide ion pairs carrying various electron-withdrawing substituents were synthesized with selected ammonium or phosphonium counterions. Compared to neutral pyridine-based organocatalysts, these new ion pair Lewis bases display superior catalytic
Tropolonate salts as acyl-transfer catalysts under thermal and photochemical conditions: Reaction scope and mechanistic insights
Mai, Binh Khanh,Koenigs, Rene M.,Nguyen, Thanh Vinh,Lyons, Demelza J.M.,Empel, Claire,Pace, Domenic P.,Dinh, An H.
, p. 12596 - 12606 (2020/11/18)
Acyl-transfer catalysis is a frequently used tool to promote the formation of carboxylic acid derivatives, which are important synthetic precursors and target compounds in organic synthesis. However, there have been only a few structural motifs known to efficiently catalyze the acyl-transfer reaction. Herein, we introduce a different acyl-transfer catalytic paradigm based on the tropolone framework. We show that tropolonate salts, due to their strong nucleophilicity and photochemical activity, can promote the coupling reaction between alcohols and carboxylic acid anhydrides or chlorides to give products under thermal or blue light photochemical conditions. Kinetic studies and density functional theory calculations suggest interesting mechanistic insights for reactions promoted by this acyl-transfer catalytic system.
The effect of the migrating group structure on enantioselectivity in lipase-catalyzed kinetic resolution?of?1-phenylethanol
Melais, Nedjma,Aribi-Zouioueche, Louisa,Riant, Olivier
, p. 971 - 977 (2016/08/08)
We have studied the effects of the acyl moiety on the enantioselectivity of three lipases: Candida antarctica B, Pseudomonas cepacia and Candida cylindracea, frequently used in kinetic resolutions by acylation or hydrolysis. The size of the acyl group was examined using various enol esters during the transesterification of 1-phenylethanol and the hydrolysis of the corresponding phenylethylesters. C. antarctica-B lipase showed the highest selectivity in the transesterification of 1-phenylethanol with isopropenyl and vinyl acetate, vinyl decanoate, vinyl laurate, (E?>?200). The esters 1-phenyl -ethyl-acetate, decanoate and laurate are also hydrolyzed with high selectivities (E?>?150) with CAL-B. The results can be correlated to the three-dimensional form of each lipase. The effect of the migrating group on the reactivity and selectivity of the lipases are discussed for both reactions.
Efficient O-Acylation of Alcohols and Phenol Using Cp2TiCl as a Reaction Promoter
Durán-Pe?a, María Jesús,Botubol-Ares, José Manuel,Hanson, James R.,Hernández-Galán, Rosario,Collado, Isidro G.
supporting information, p. 3584 - 3591 (2016/07/28)
A method has been developed for the conversion of primary, secondary, and tertiary alcohols, and phenol, into the corresponding esters at room temperature. The method uses a titanium(III) species generated from a substoichiometric amount of titanocene dichloride together with manganese(0) as a reductant, as well as methylene diiodide. It involves a transesterification from an ethyl ester, or a reaction with an acyl chloride. A radical mechanism is proposed for these transformations.
NOVEL PYRIDINE OXIDE COMPOUND, AND PROCESS FOR PRODUCING CARBOXYLIC ACID DERIVATIVE AND OPTICALLY ACTIVE CARBOXYLIC ACID DERIVATIVE WITH THE USE OF THE SAME
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Page/Page column 7-8, (2009/04/24)
The invention relates to a pyridine oxide compound represented by formula (I), an optically active compound thereof, a salt thereof and a hydrate thereof, and, in the presence of the compound as a catalyst, performing 1) a method for producing an ester compound or an amide compound from a carboxylic acid equivalent and an alcohol or an amine, 2) an asymmetric esterification reaction or 3) an asymmetric amidation reaction. In formula (I), each R1 may be the same as the other R1 or different and each R1 represents an alkyl group, an aromatic group, a heterocyclic group, a carboxyl group, an ester group, a cyano group, a halogen atom, an oxygen atom, a sulfur atom or a nitrogen atom; each R2 may be the same as the other R2 or different and each R2 represents a hydrogen atom, an alkyl group, an aromatic group, a heterocyclic group, a carboxyl group, an ester group, a cyano group, a halogen atom, an oxygen atom or the like, and R3 and R4 may be the same or different and R3 and R4 each represent a hydrogen atom, an alkyl group, an aromatic group, a heterocyclic group, a carboxyl group, an ester group, a cyano group, a halogen atom, an oxygen atom or the like.
Dual behavior of alcohols in iodine-catalyzed esterification under solvent-free reaction conditions
Jereb, Marjan,Vra?i?, Dejan,Zupan, Marko
scheme or table, p. 2347 - 2352 (2009/09/06)
The dual behavior phenomenon of alcohols in iodine-catalyzed esterification under solvent-free reaction conditions (SFRCs) is described; the governing factor is the stability of the carbonium ion generated from the alcohol; high concentration reaction conditions (HCRCs) or dilute solutions are much less suitable. In the case of benzylic alcohols, loss of optical activity was noted, whereas alkyl alcohols furnished a product with retention of stereochemistry.
Bismuth Oxide Perchlorate as a Highly Efficient Catalyst for Heteroatom Acylation under Solvent-Free Conditions
Chakraborti, Asit K.,Gulhane, Rajesh,Shivani
, p. 1805 - 1808 (2007/10/03)
Bismuth oxide perchlorate efficiently catalyzes the acetylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Sterically hindered and electron deficient phenols are acetylated in excellent yields with stoichiometric amounts of Ac2O at room temperature. Acylation of acid-sensitive alcohols is carried out efficiently without competitive side reactions. Optically active substrates are acetylated without any detrimental effect on the optical purity.
Highly powerful and practical acylation of alcohols with acid anhydride catalyzed by Bi(OTf)3
Orita,Tanahashi,Kakuda,Otera
, p. 8926 - 8934 (2007/10/03)
Bi(OTf)3-catalyzed acylation of alcohols with acid anhydride was evaluated in comparison with other acylation methods. The Bi(OTf)3/acid anhydride protocol was so powerful that sterically demanding or tertiary alcohols could be acylated smoothly. Less reactive acylation reagents such as benzoic and pivalic anhydride are also activated by this catalysis. In these cases, a new technology was developed in order to overcome difficulty in separation of the acylated product from the remaining acylating reagent: methanolysis of the unreacted anhydride into easily separable methyl ester realized quite easy separation of the desired acylation product. The Bi(OTf)3/acid anhydride protocol was applicable to a wide spectrum of alcohols bearing various functionalities. Acid-labile THP- or TBS-protected alcohol, furfuryl alcohol, and geraniol could be acylated as well as base-labile alcohols. Even acylation of functionalized tertiary alcohols was effected at room temperature.
Generation of allylic and benzylic organolithium reagents from the corresponding ester, amide, carbonate, carbamate and urea derivatives
Alonso, Emma,Guijarro, David,Martinez, Pedro,Ramon, Diego J.,Yus, Miguel
, p. 11027 - 11038 (2007/10/03)
The reaction of different allylic and benzylic non-enolisable esters or amides (1), carbonates (4), carbamates (6, 7) and ureas (8) with an excess of lithium powder and a catalytic amount of naphthalene (10%) in the presence of an electrophile [(i)PrCHO, (t)BuCHO, PhCHO, Me2CO, Et2CO, (CH2)5CO, Ph2CO, Me3SiCl] in THF at different temperatures (-78, -30 or 0°C) leads, after hydrolysis with water to the corresponding allylated or benzylated products (2).
