50874-07-2Relevant academic research and scientific papers
Enantioselective Desymmetrization of 2-Aryl-1,3-propanediols by Direct O-Alkylation with a Rationally Designed Chiral Hemiboronic Acid Catalyst That Mitigates Substrate Conformational Poisoning
Estrada, Carl D.,Ang, Hwee Ting,Vetter, Kim-Marie,Ponich, Ashley A.,Hall, Dennis G.
supporting information, (2021/04/07)
Enantioselective desymmetrization by direct monofunctionalization of prochiral diols is a powerful strategy to prepare valuable synthetic intermediates in high optical purity. Boron acids can activate diols toward nucleophilic additions; however, the design of stable chiral catalysts remains a challenge and highlights the need to identify new chemotypes for this purpose. Herein, the discovery and optimization of a bench-stable chiral 9-hydroxy-9,10-boroxarophenanthrene catalyst is described and applied in the highly enantioselective desymmetrization of 2-aryl-1,3-diols using benzylic electrophiles under operationally simple, ambient conditions. Nucleophilic activation and discrimination of the enantiotopic hydroxy groups on the diol substrate occurs via a defined chairlike six-membered anionic complex with the hemiboronic heterocycle. The optimal binaphthyl-based catalyst 1g features a large aryloxytrityl group to effectively shield one of the two prochiral hydroxy groups on the diol complex, whereas a strategically placed "methyl blocker"on the boroxarophenanthrene unit mitigates the deleterious effect of a competing conformation of the complexed diol that compromised the overall efficiency of the desymmetrization process. This methodology affords monoalkylated products in enantiomeric ratios equal or over 95:5 for a wide range of 1,3-propanediols with various 2-aryl/heteroaryl groups.
Arylation of diethyl malonate and ethyl cyanoacetate catalyzed by palladium/di-tert-butylneopentylphosphine
Semmes, Jeffrey G.,Bevans, Stephanie L.,Mullins, C. Haddon,Shaughnessy, Kevin H.
supporting information, p. 3447 - 3450 (2015/02/05)
α-Arylated carbonyl derivatives are important structural motifs in many natural products and pharmaceutically active compounds. Although arylation of simple monocarbonyl compounds is a well-established methodology, metal-catalyzed arylation of β-dicarbonyl derivatives is significantly more challenging. The ability of β-dicarbonyl anions to bind to palladium in a κ2-O,O mode, rather than the κ1-C-bound mode required for bond formation, often results in the deactivation of catalyst systems. The C-bound form of the enolate can be favored through the use of sterically demanding ligands. Herein, we report that the sterically demanding di-tert-butylneopentylphosphine (DTBNpP) ligand in combination with Pd(dba)2 provides an effective catalyst for the coupling of aryl bromides and chlorides with diethyl malonate. The Pd/DTBNpP system also catalyzes the coupling of aryl bromides with ethyl cyanoacetate.
Rh(I)-catalyzed cross-coupling of α-diazoesters with arylsiloxanes
Xia, Ying,Liu, Zhen,Feng, Sheng,Ye, Fei,Zhang, Yan,Wang, Jianbo
supporting information, p. 956 - 959 (2015/03/30)
An Rh(I)-catalyzed cross-coupling of diazoesters with arylsiloxanes has been successfully achieved. This transformation is a new method for the construction of the C(sp3)-C(sp2) bond, thus providing an alternative synthesis of α-aryl esters. Rh(I)-carbene migratory insertion has been proposed to be involved in this coupling reaction. The reaction represents the first example of utilizing arylsiloxane as the coupling partner in the carbene-involved cross-coupling reactions.
Enzymatic desymmetrization of prochiral 2-substituted-1,3-diamines: Preparation of valuable nitrogenated compounds
Rios-Lombardia, Nicolas,Busto, Eduardo,Garcia-Urdiales, Eduardo,Gotor-Fernandez, Vicente,Gotor, Vicente
supporting information; experimental part, p. 2571 - 2574 (2009/07/25)
A wide range of prochiral 1, 3-diamines were first efficiently synthesized and subsequently desymmetrized by using lipase from Pseudomonas cepacia as catalyst and diallyl carbonate as alkoxycarbonylating agent. In all cases, the amino carbamates of R-configuration were recovered. Final selective cleavage of the N-allyloxycarbonyl moiety was carried out under mild reaction conditions, which demonstrates the high versatility and potential of this chemoenzymatic route as a source of intermediates in the synthesis of related optically active nitrogenated derivatives.
Pyrimidine Non-Classical Cannabinoid Compounds and Related Methods of Use
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Page/Page column 8, (2009/12/05)
Disclosed are compounds of the formula I: wherein R1, R2, V, W, X, Y and Z can be as defined herein. The compounds can be used in the treatment of disorders mediated by the cannabinoid receptors.
Pyridine Non-Classical Cannabinoid Compounds and Related Methods of Use
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Page/Page column 6, (2009/12/05)
wherein R1, R2, V, W, X, Y and Z can be as defined herein. The compounds can be used in the treatment of disorders mediated by the cannabinoid receptors.
Room-temperature copper-catalyzed α-arylation of malonates
Yip, Sau Fan,Cheung, Hong Yee,Zhou, Zhongyuan,Kwong, Fuk Yee
, p. 3469 - 3472 (2008/02/12)
An effective method in targeting α-aryl malonates is reported. In the presence of a catalytic amount of 2-picolinic acid and Cul, the coupling of aryl iodides with diethyl malonate proceeds smoothly even at room temperature. The high levels of functional group compatibility and exceptionally mild reaction conditions offer this an attractive protocol in accessing a variety of arylated malonates.
CuI/L-proline-catalyzed coupling reactions of aryl halides with activated methylene compounds
Xie, Xiaoan,Cai, Guorong,Ma, Dawei
, p. 4693 - 4695 (2007/10/03)
(Chemical Equation Presented) The arylation of ethyl acetoacetate, ethyl benzoyl acetate, and diethyl malonate under the catalysis of Cul/L-proline in DMSO proceeds smoothly at 40-50°C in the presence of Cs2CO 3 to provide the 2-aryl
Asymmetric synthesis of benzylic quaternary carbon center via an enzymatic reaction
Shiotani, Shunsaku,Okada, Hirohiko,Nakamata, Kumiko,Yamamoto, Takako,Sekino, Fumie
, p. 1031 - 1047 (2007/10/03)
(R)-(+)- ((R)-(+)-12) and(S)-(-)-1-formyl-1-methyl-7-methoxy-1,2,3,4-tetrahydronaphthalene((S)-(-)-12) were synthesized based on enantioselective PLE hydrolysis of diethyl 2-(m-methoxyphenyl)-2-methylmalonate. From (R)-(+)-12, (+)-O-Methylaphanorphine (16
Ester Enolates from α-Acetoxy Esters. Synthesis of Aryl Malonic and α-Aryl Alkanoic Esters from Aryl Nucleophiles and α-Keto Esters
Ghosh, Subrata,Pardo, Simon N.,Salomon, Robert G.
, p. 4692 - 4702 (2007/10/02)
Ester enolates are generated by reductive α-deacetoxylation of α-acetoxy-α-arylmalonic esters or α-acetoxy-α-arylalkanoic esters with lithium in liquid ammonia or sodium α-(dimethylamino)naphthalenide in hexamethylphosphoramide-benzene.Since the requisite α-acetoxy esters are available from aryl nucleophiles, the reductions provide effective new synthetic routes to arylmalonic esters and α-arylalkanoic esters.For example, 2-(p-isobutylphenyl)propionic acid (ibuprofen, a commercially important nonsteroidal antiinflammatory agent) is obtained in 73percent yield overall from isobutylbenzene.Arenes, aryllithiums, or arylmagnesium halides react with α-keto esters, e.g., diethyl oxomalonate, ethyl pyruvate, methyl phenylglyoxalate, or alkyl glyoxylates, to afford α-hydroxy esters.These are acetylated with acetic anhydride-triethylamine and p-(dimethylamino)pyridine as a catalyst.Reductive α-deoxygenation then allows replacement of the acetoxy group by hydrogen or an alkyl group.
