31786-45-5Relevant articles and documents
Dihydroisocoumarin derivative and preparation method and application thereof
-
, (2022/01/10)
The present invention discloses a dihydroisocoumarin derivative and preparation method and application thereof, the dihydroisocoumarin derivative having a structure as shown in formula (I) or (II). The method of preparing dihydroisocoumarin derivatives of
Dihydroisocoumarin derivative and preparation method and application thereof
-
, (2022/01/10)
The present invention discloses a dihydroisocoumarin derivative and preparation method and application thereof, the dihydroisocoumarin derivative having a structure as shown in formula (I) or (II). The method of preparing dihydroisocoumarin derivatives of
Zn-Catalyzed Enantio- and Diastereoselective Formal [4 + 2] Cycloaddition Involving Two Electron-Deficient Partners: Asymmetric Synthesis of Piperidines from 1-Azadienes and Nitro-Alkenes
Chu, John C. K.,Dalton, Derek M.,Rovis, Tomislav
supporting information, p. 4445 - 4452 (2015/04/14)
We report a catalytic asymmetric synthesis of piperidines through [4 + 2] cycloaddition of 1-azadienes and nitro-alkenes. The reaction uses earth abundant Zn as catalyst and is highly diastereo- and regioselective. A novel BOPA ligand (F-BOPA) confers high reactivity and enantioselectivity in the process. The presence of ortho substitution on the arenes adjacent to the bis(oxazolines) was found to be particularly impactful, due to limiting the undesired coordination of 1-azadiene to the Lewis acid and thus allowing the reaction to be carried out at lower temperature. A series of secondary kinetic isotope effect studies using a range of ligands implicates a stepwise mechanism for the transformation, involving an initial Michael-type addition of the imine to the nitro-alkene followed by a cyclization event. The stepwise mechanism obviates the electronic requirement inherent to a concerted mechanism, explaining the successful cycloaddition between two electron-deficient partners. (Chemical Equation Presented).
First general, direct, and regioselective synthesis of substituted methoxybenzoic acids by ortho metalation
Nguyen, Thi-Huu,Chau, Nguyet Trang Thanh,Castanet, Anne-Sophie,Nguyen, Kim Phi Phung,Mortier, Jacques
, p. 3419 - 3429 (2008/02/03)
(Chemical Equation Presented) New general methodology of value in aromatic chemistry based on ortho-metalation sites in o-, m-, and p-anisic acids (1-3) (Scheme 1) is described. The metalation can be selectively directed to either of the ortho positions by varying the base, metalation temperature, and exposure times. Metalation of o-anisic acid (1) with s-BuLi/TMEDA in THF at -78°C occurs exclusively in the position adjacente to the carboxylate. On the other hand, a reversal of regioselectivity is observed with n-BuLi/t-BuOK. With LTMP at 0°C, the two directors of m-anisic acid (2) function in concert to direct introduction of the metal between them while n-BuLi/t-BuOK removes preferentially the proton located ortho to the methoxy and para to the carboxylate (H-4). s-BuLi/TMEDA reacts with p-anisic acid (3) exclusively in the vicinity of the carboxylate. According to these methodologies, routes to very simple methoxybenzoic acids with a variety of functionalities that are not easily accessible by other means have been developed (Table 1).
Regioselective halogen-metal exchange reaction of 3-substituted 1,2-dibromo arenes: The synthesis of 2-substituted 5-bromobenzoic acids
Menzel, Karsten,Dimichele, Lisa,Mills, Paul,Frantz, Doug E.,Nelson, Todd D.,Kress, Michael H.
, p. 1948 - 1952 (2008/02/08)
Regioselective halogen-metal exchange reactions using isopropylmagnesium chloride were carried out on 3-substituted 1,2-dibromo arenes. Eleven examples are given. Georg Thieme Verlag Stuttgart.
Halogen-metal exchange of 3-substituted 1,2-dibromoarenes: The use of long-range JCH coupling constants to determine regiochemistry
DiMichele, Lisa,Menzel, Karsten,Mills, Paul,Frantz, Doug,Nelson, Todd
, p. 1041 - 1043 (2008/02/05)
Regioselective halogen/metal exchange reactions were carried out on a series of 3-substituted-1,2-dibromoarenes. Product mixtures were quenched with CO2 to form the corresponding benzoic acid analogs to facilitate HPLC and NMR analysis. Substitution at the 3-position could readily be assigned on the basis of 2D HMBC long-range correlations, while assignment at the 2-position was not as straightforward. The use of three-bond JCH coupling constant measurements, extracted from 1-D 1H coupled 13C experiments, were necessary to render unequivocal regio assignments. Copyright
Directed ortho-metalation of unprotected benzoic acids. Methodology and regioselective synthesis of useful contiguously 3- and 6-substituted 2-methoxybenzoic acid building blocks
Nguyen, Thi-Huu,Castanet, Anne-Sophie,Mortier, Jacques
, p. 765 - 768 (2007/10/03)
By treatment with s-BuLi/TMEDA at -78 °C, unprotected 2-methoxybenzoic acid is deprotonated exclusively in the position ortho to the carboxylate. A reversal of regioselectivity is observed when the acid is treated with n-BuLi/t-BuOK. These results are of general utility for the one-pot preparation of a variety of very simple 3- and 6-substituted 2-methoxybenzoic acids that are not easily accessible by conventional means. The potential usefulness of the method is demonstrated by the expedient synthesis of lunularic acid.
Synthesis of a 6H-pyrazolo[4,5,1-de]acridin-6-one derivative: A useful intermediate of antitumour agents
Sugaya,Mimura,Kato,Ikuta,Mimura,Kasai,Tomioka
, p. 73 - 76 (2007/10/02)
A 6H-pyrazolo[4,5,1-de]acridin-6-one derivative, a useful intermediate of antitumor agents, was prepared by a facile synthetic route from 2-bromobenzoic acid and 6-nitroindazole involving a halogenocopper(I)-catalyzed Ullmann coupling reaction and Friedel-Crafts cyclization.
Reductive Dechlorination of Chloro-phenols and -benzoic acids by Raney Co-Al Alloy in an Alkaline Deuterium Oxide Solution and Preparation of Deuterated Salicylic Acids
Tashiro, Masashi,Tsuzuki, Hirohisa,Matsumoto, Jun-ichi,Mataka, Shuntaro,Nakayama, Kouji,et al.
, p. 2826 - 2851 (2007/10/02)
Reduction of monochloro-phenols (1a-c) and -benzoic acids (3a-c) by using Raney Co-Al alloy in 10percent NaOD-D2O gave phenols (2a-c) and benzoic acids (4a-c) in 86-93percent isotopic purities.The reduction of di-, tri-, and tetra-chlorinated derivatives, (1) and (3), gave the deuteriated products, (2) and (4), in somewhat low isotopic purities (70-84percent).In the reduction of polychlorinated benzoic acids (3), the use of a mixed solution (1/1 = v/v) of 10percent Na2CO3-D2O and 10percent NaOD-D2O was effective and gave 4 in 80-89percent isotopic purities.The treatment of chlorosalicylic acids (5) with Raney Co-Al alloy in 10percent NaOD-D2O gave 1> (6) - 3> (6) in 91-93percent isotopic purities.