52826-41-2Relevant academic research and scientific papers
Copper-catalyzed tri- or tetrafunctionalization of alkenylboronic acids to prepare tetrahydrocarbazol-1-ones and indolo[2,3-a]carbazoles
Bi, Hong-Yan,Li, Cheng-Jing,Liang, Cui,Mo, Dong-Liang,Wei, Cui
supporting information, p. 5815 - 5821 (2020/09/21)
We describe a cascade strategy for tri- or tetrafunctionalization of alkenylboronic acids to prepare diverse tetrahydrocarbazol-1-ones and indolo[2,3-a]carbazoles in good yields withN-hydroxybenzotriazin-4-one (HOOBT) and arylhydrazines as oxygen and nitrogen sources, respectively. Mechanistic studies reveal that the domino reaction undergoes the copper-catalyzed Chan-Lam reaction, [2,3]-rearrangement, nucleophilic substitution, oxidation and sequential [3,3]-rearrangement over five steps in a one-pot reaction. The reaction shows a broad substrate scope and tolerates a wide range of functional groups. More importantly, the reaction is easily performed at gram scales and the product is purified by simple extraction, washing, and recrystallization without flash column chromatography. The present protocol features easily available starting materials, high site-marked functionalization, five-step cascade in one pot, multiple C-C/C-O/C-N bond formation, and diversity of indole motifs.
Umpolung-like Cross-coupling of Tosylhydrazones with 4-Hydroxy-2-pyridones under Palladium Catalysis
Katsina, Tania,Papoulidou, Kyriaki Eleni,Zografos, Alexandros L.
supporting information, p. 8110 - 8115 (2019/10/11)
Tosylhydrazones under palladium catalysis were found to perform cross-coupling reactions with 4-hydroxy-2-pyridones. The umpolung-like reactivity, between the α-carbon of tosylhydrazone and the 3-position of the heterocycle, which is observed in the obtai
Pd-Catalyzed Heck-Type Reaction: Synthesizing Highly Diastereoselective and Multiple Aryl-Substituted P-Ligands
Li, Chong,Qiang, Xiao-Yue,Qi, Zhi-Chao,Cao, Bin,Li, Jing-Yu,Yang, Shang-Dong
supporting information, p. 7138 - 7142 (2019/09/30)
In this work, an efficient palladium-catalyzed Heck-type reaction was successfully used to synthesize a wide range of monoaryl-or diaryl-substituted P-ligands with excellent yields and diastereoselectivity (up to 98% yield, dr >20:1). The preliminary mechanistic studies demonstrated that it possibly underwent a cationic Heck reaction that was assisted by silver salt, and it revealed the significant role of P(O)Ar2 for excellent yields and diastereoselectivity.
Regioselective preparation of saturated spirocyclic and ring-expanded fused pyrazoles
Merchant, Rohan R.,Allwood, Daniel M.,Blakemore, David C.,Ley, Steven V.
, p. 8800 - 8811 (2015/01/08)
Saturated bicyclic pyrazoles represent an important class of biologically active molecules, but their preparation can be hampered by labor-intensive synthesis of required starting materials. A convenient one- or two-step procedure for the synthesis of sat
Tetraethylammonium bromide catalysed phase transfer reaction of potassium superoxide with hydrazones and tosylhydrazones
Kumar,Singh
, p. 579 - 583 (2007/10/03)
A variety of hydrazones and tosylhydrazones of carbonyl compounds have been investigated under the mild reaction conditions of potassium superoxide and tetraethylammonium bromide in dry dimethylformamide. As a result, hydrazones are generally transformed to their corresponding azines whereas tosylhydrazones undergo facile fragmentation to give the olefinic products in fairly good yields. The study highlights the use of tetraethylammonium bromide as an efficient and inexpensive catalyst for superoxide studies.
Elucidation of the catalytic mechanisms of the non-haem iron-dependent catechol dioxygenases: Synthesis of carba-analogues for hydroperoxide reaction intermediates
Winfield, Christopher J.,Al-Mahrizy, Zeyana,Gravestock, Michael,Bugg, Timothy D.H.
, p. 3277 - 3289 (2007/10/03)
The catalytic mechanisms of the non-haem iron-dependent intradiol and extradiol catechol dioxygenases are thought to involve transient hydroperoxide reaction intermediates, formed by reaction of a catechol substrate with dioxygen. The synthesis of carba-analogues of these intermediates is described in which the hydroperoxide functional group (-OOH) is replaced by a hydroxymethyl group (-CH2OH), and the cyclohexadienone skeleton simplified to a cyclohexanone. Analogues of the "proximal" hydroperoxide in which the hydroxymethyl group was positioned axially with respect to the ring were found to act as reversible competitive inhibitors (Ki 0.7-7.6 mM) for the extradiol enzyme 2,3-dihydroxyphenylpropionate 1,2-dioxygenase (MhpB) from Escherichia coli, whereas analogues in which the hydroxymethyl group was positioned equatorially showed no inhibition. In contrast, assays versus the intradiol-cleaving protocatechuate 3,4-dioxygenase from Pseudomonas sp. showed inhibition only by an analogue containing an equatorial hydroxymethyl group (IC50 9.5 mM). These data support the existence of a proximal hydroperoxide intermediate in the extradiol catechol dioxygenase mechanism, and suggest that the conformation adopted by the hydroperoxide reaction intermediate may be an important determinant in the reaction specificity of the extradiol and intradiol dioxygenases. The Royal Society of Chemistry 2000.
