5657-01-2Relevant academic research and scientific papers
Chiral Bicyclic Imidazole-Catalyzed Acylative Dynamic Kinetic Resolution for the Synthesis of Chiral Phthalidyl Esters
Zhou, Muxing,Gridneva, Tatiana,Zhang, Zhenfeng,He, Ende,Liu, Yangang,Zhang, Wanbin
supporting information, p. 1641 - 1645 (2020/11/30)
Utilizing a chiral bicyclic imidazole organocatalyst and adopting a continuous injection process, an alternative route has been developed for the efficient synthesis of chiral phthalidyl ester prodrugs via dynamic kinetic resolution of 3-hydroxyphthalides through enantioselective acylation (up to 99 % ee). The computational studies suggest a general base catalytic mechanism differing from the widely accepted nucleophilic catalytic mechanism. The structure analysis of the key transition states shows that the CH-π interactions and not the previously considered cation/π-π interactions between the catalyst and substrate is the dominant factor giving rise to the observed stereocontrol.
Visible Light-Promoted Magnesium, Iron, and Nickel Catalysis Enabling C(sp3)-H Lactonization of 2-Alkylbenzoic Acids
Li, Sasa,Su, Mincong,Sun, Jie,Hu, Kunjun,Jin, Jian
supporting information, p. 5842 - 5847 (2021/07/31)
A mild and practical C(sp3)-H lactonization protocol has been achieved by merging photocatalysis and magnesium (iron, nickel) catalysis. A diverse range of 2-alkylbenzoic acids with a variety of substitution patterns could be transformed into the corresponding phthalide products. Based on the mechanistic experimentation and reported prior studies, a possible mechanism for the benzylic oxidative lactonization reaction was proposed with the hypothetic photoactive ternary complex formed between the 2-alkylbenzoic acid substrate, magnesium ion, and bromate anion.
Ligand-enabled pd(ii)-catalyzed c(sp3)-h lactonization using molecular oxygen as oxidant
Qian, Shaoqun,Li, Zi-Qi,Li, Minyan,Wisniewski, Steven R.,Qiao, Jennifer X.,Richter, Jeremy M.,Ewing, William R.,Eastgate, Martin D.,Chen, Jason S.,Yu, Jin-Quan
supporting information, p. 3960 - 3963 (2020/05/22)
Pd(II)-catalyzed C-H lactonization of o-methyl benzoic acid substrates has been achieved using molecular oxygen as the oxidant. This finding provides a rare example of C-H oxygenation through Pd(II)/Pd(0) catalysis as well as a method to construct biologically important benzolactone scaffolds. The use of a gas mixture of 5% oxygen in nitrogen demonstrated the possibility for its application in pharmaceutical manufacturing.
A Five-Step Cascade for the Modular and Regiodefined Synthesis of Naphth[2,1-d]oxazoles
Dinda, Bidyut Kumar,Basak, Shyam,Ghosh, Bidhan,Mal, Dipakranjan
supporting information, p. 1235 - 1245 (2016/05/11)
The reaction of 3-nucleofugal phthalides with 2-amidoacrylates is shown to provide a synthesis of densely substituted naphth[2,1-d]oxazoles in good yields. It is proposed to proceed via a five-step cascade which includes phthalide annulation, demethoxycarbonylation, and heterocyclization. The methodology is free from regiochemical ambiguity of the products. In certain cases, the corresponding 2-amidonaphthoquinones are directly formed.
Pt-Catalyzed sp3 C-H bond activation of o-alkyl substituted aromatic carboxylic acid derivatives for the formation of aryl lactones
Lee, Ji Min,Chang, Sukbok
, p. 1375 - 1379 (2007/10/03)
Synthesis of aryl lactones from ortho-alkyl substituted aromatic carboxylic acids is described on the basis of sp3 C-H bond activation using either palladium or platinum catalysts. Kinetic isotope studies reveal that the reaction takes place presumably by the chelation assistance of metal catalyst to the carboxylic group followed by the C-H bond activation.
Fast microwave promoted palladium-catalyzed synthesis of phthalides from bromobenzyl alcohols utilizing DMF and Mo(CO)6 as carbon monoxide sources
Wu, Xiongyu,Mahalingam,Wan, Yiqian,Alterman, Mathias
, p. 4635 - 4638 (2007/10/03)
A fast method utilizing in situ generated CO for the synthesis of phthalides has been developed. DMF and Mo(CO)6 were applied as two alternative CO-sources in these microwave promoted carbonylation-lactone formation reactions. Mo(CO)6 was found to be the more generally applicable CO-source and provided phthalides as well as dihydroisocoumarin, dihydroisoindone, and phthalimide from the corresponding aryl bromide via an efficient CO insertion within a 1h reaction time.
Cycloadducts of Arynes with 1,3-Bis(trimethylsilyl)naphthofuran: Formation of Novel Polycyclic Aromatic Derivatives and Related Reactions
Pollart, Daniel J.,Rickborn, Bruce
, p. 3155 - 3161 (2007/10/02)
A recently developed procedure for the preparation of trimethylsilylated isobenzofurans and the use of these materials in cycloaddition reactions has been extended to an isonaphthofuran analogue.The 1,3-bis(trimethylsilyl)naphthofuran (7) has been isolated; its reaction with maleic anhydride in room temperature is rapid and readily reversible as shown by endo to exo cycloadduct interconversion.The failure of 7 to give cycloadduct with 2-butenolide indicates that it is less reactive than the parent naphthofuran.In situ generation and cycloaddition reactions with various arynes (benzyne, 4-methylbenzyne, 3,4-pyridyne, 9,10-phenanthrolyne, 1,2-naphthalyne, 2,3-naphthalyne) are described.The three unsymmetrical arynes all give mixtures of cycloadducts indicative of negligible regioselectivity in Diels-Alder reactions with 7; thus, in spite of possible steric hindrance the reaction with 1,2-naphthalyne gives a 1:1 mixture of dibenz- and dibenzanthracene derivatives.In contrast, the reaction of 1-ethoxy-3-(trimethylsilyl)naphthoanthracene derivative.Various reactions of the cycloadducts are described.
Benzoisobenzofuran. Formation and Reactions of the Parent and Alkoxy-Substituted Derivatives
Cornejo, Jaime J.,Ghodsi, Shahram,Johnson, R. Douglas,Woodling, Rick,Rickburn, Bruce
, p. 3869 - 3876 (2007/10/02)
Benzoisobenzofuran (1) is formed by base-induced 1,4-elimination of either acetal 9 or 11 and may be isolated in high yield as a cristalline solid.Cycloaddition reactions of preformed 1 have been carried out with various dienophiles.These reactions may also be accomplished by heating the acetals in the presence of dienophiles and acid catalyst, where 1 is generated as an intermediate.The cycloaddition reaction of 1 and maleic anhydride is found to be reversible at higher temperature (slow at 60 deg C).Unsymmetrical dienophiles react with 1 to give equal amounts of regioisomers, and evidence points to lack of regioselectivity under both kinetically controlled and equilibrating conditions.The acetals 9 and 11 are shown to interconvert with acid catalyst at 140 deg C, where 1 is an intermediate of greater stability than the acetals; the equilibrium K for 9 -> ( - ) 11 is approximately unity.Various acid-catalyzed cycloaddition reactions of ortho esters 8 and 10, yielding polysubstituted phenanthrene derivatives, are described.
