210536-20-2Relevant articles and documents
Iron-Catalyzed Reductive Cyclization by Hydromagnesiation: A Modular Strategy Towards N-Heterocycles
Larin, Egor M.,Lautens, Mark,Loup, Joachim
supporting information, p. 22345 - 22351 (2021/09/09)
A reductive cyclization to prepare a variety of N-heterocycles, through the use of ortho-vinylanilides, is reported. The reaction is catalyzed by an inexpensive and bench-stable iron complex and generally occurs at ambient temperature. The transformation likely proceeds through hydromagnesiation of the vinyl group, and trapping of the in situ generated benzylic anion by an intramolecular electrophile to form the heterocycle. This iron-catalyzed strategy was shown to be broadly applicable and was utilized in the synthesis of substituted indoles, oxindoles and tetrahydrobenzoazepinoindolone derivatives. Mechanistic studies indicated that the reversibility of the hydride transfer step depends on the reactivity of the tethered electrophile. The synthetic utility of our approach was further demonstrated by the formal synthesis of a reported bioactive compound and a family of natural products.
Palladium-Catalyzed Carbamoyl-Carbamoylation/ Carboxylation/Thioesterification of Alkene-Tethered Carbamoyl Chlorides Using Mo(CO)6 as the Carbonyl Source
Chen, Chen,Ding, Jie,Huang, Yujie,Liu, Liying,Zhu, Bolin
supporting information, (2022/01/04)
We reported a palladium-catalyzed carbamoyl-carbamoylation/carboxylation/thioesterification of alkene-tethered carbamoyl chlorides using Mo(CO)6 as the carbonyl source. The reactions were typically performed with good functional group compatibility and tolerated different nucleophiles (amines, alcohols, phenols, thiols and water), which provided a new access to amidated/esterificated/thioesterificated/carboxylated oxindoles or lactams bearing an all-carbon quaternary stereocenter under CO gas-free conditions. Furthermore, natural product mutation and divergent late-stage derivatization are the important practical features.
Chemoselectivity for Alkene Cleavage by Palladium-Catalyzed Intramolecular Diazo Group Transfer from Azide to Alkene
Frost, Grant B.,Mittelstaedt, Michaela N.,Douglas, Christopher J.
supporting information, p. 1727 - 1732 (2019/01/09)
Alkenes can be cleaved by means of the (3+2) cycloaddition and subsequent cycloreversion of 1,3-dipoles, classically ozone (O3), but the azide (R?N3) variant is rare. Chemoselectivity for these azide to alkene diazo group transfers (DGT) is typically disfavored, thus limiting their synthetic utility. Herein, this work discloses a palladium-catalyzed intramolecular azide to alkene DGT, which grants chemoselectivity over competing aziridination. The data support a catalytic cycloreversion mechanism distinct from other known metal-catalyzed azide/alkene reactions: nitrenoid/metalloradical and (3+2) cycloadditions. Kinetics experiments reveal an unusual mechanistic profile in which the catalyst is not operative during the rate-controlling step, rather, it is active during the product-determining step. Catalytic DGT was used to synthesize N-heterocyclic quinazolinones, a medicinally relevant structural core. We also report on the competing aziridination and subsequent ring expansion to another N-heterocyclic core structure of interest, benzodiazepinones.
Ring-closing metathesis of vinyl fluorides towards α-fluorinated α,β-unsaturated lactams and lactones
Marhold, Michael,Stillig, Christian,Fr?hlich, Roland,Haufe, Günter
supporting information, p. 5777 - 5785 (2014/10/15)
Ring-closing olefin metathesis reactions (RCM) using Grubbs II or Hoveyda's catalysts have been applied to a series of N-alkenyl-N-benzyl-α-fluoroacrylamides. α-Fluoro-α,β-unsaturated γ- or δ-lactams incorporating a fluorinated double bond were obtained in moderate to good yields, depending on the nature of substituents on the benzyl ring. The corresponding seven- and eight-membered lactams were not formed under similar conditions. When the N-benzyl group was replaced by an N-tosyl group, the corresponding ε-lactam was also formed in 38% yield. When N-(2-fluoroallyl) derivatives were used instead of fluoroacryloyl derivatives, six-, seven-, and eight-membered N-heterocycles were obtained in low yields. This method was also used to synthesize fluorinated α,β-unsaturated analogues of pyrrolizidine and indolizidine alkaloids from prolinol, and also to synthesize N-benzyl-3-fluoroquinolone in three steps from commercially available 2-vinylaniline in 44% overall yield. Also 3-fluorocoumarin and 3-fluorochromene were prepared from ovinylphenol, and 3-fluoro-benzoxepine was available from o-allylphenol.
A convergent, modular approach to functionalized 2,1-borazaronaphthalenes from 2-aminostyrenes and potassium organotrifluoroborates
Wisniewski, Steven R.,Guenther, Courtney L.,Andreea Argintaru,Molander, Gary A.
, p. 365 - 378 (2014/01/17)
Azaborines are an important class of compounds with applications in both medicinal chemistry and materials science. The first borazaronaphthalene, 2-chloro-2,1-borazaronaphthalene, was reported in 1959; however, access to more highly functionalized substructures has been limited because of the harsh reaction conditions required to displace the chloride on boron. A convergent approach has been developed to synthesize disubstituted 2,1-borazaronaphthalenes from N-substituted 2-aminostyrenes and potassium organotrifluoroborates, where the potassium organotrifluoroborate is converted to the active R-BX2 species (X = Cl or F) in situ by addition of a fluorophile. Starting from aryl-, heteroaryl-, alkynyl-, alkenyl-, and alkyltrifluoroborates, a library of highly functionalized 2,1-borazaronaphthalenes were synthesized in one step under mild, transition-metal-free conditions.
One-pot ring-closing metathesis/1,3-dipolar cycloaddition through assisted tandem ruthenium catalysis: Synthesis of a dye with isoindolo[2,1-a]quinoline structure
Arisawa, Mitsuhiro,Fujii, Yuki,Kato, Hiroshige,Fukuda, Hayato,Matsumoto, Takashi,Ito, Mika,Abe, Hiroshi,Ito, Yoshihiro,Shuto, Satoshi
supporting information, p. 1003 - 1007 (2013/03/13)
The one-pot tandem reaction of N-alkyl-N-allyl-2-vinylaniline derivatives with benzo- or naphthoquinones and a ruthenium-alkylidene catalyst leads to isoindolo[2,1-a]quinolines in a variety of colors, which can be altered by exchanging the substituent on the core heterocycle (see scheme). This reaction offers a new synthetic method for π-conjugated small molecules from simple aniline derivatives. Copyright
Thermal switchability of N-chelating hoveyda-type catalyst containing a secondary amine ligand
Zukowska, Karolina,Szadkowska, Anna,Pazio, Aleksandra E.,Wo?niak, Krzysztof,Grela, Karol
experimental part, p. 462 - 469 (2012/04/23)
An investigation of aza analogues of the popular Hoveyda-Grubbs catalyst containing a secondary amine ligand is presented, proving the crucial impact of steric as well as electronic factors on the catalyst's stability and performance. The issue of latency in the reactivity profile of studied catalysts is examined, followed by structural and application studies.
Indole synthesis by controlled carbolithiation of o-aminostyrenes
Kessler, Albane,Coleman, Claire M.,Charoenying, Patchanee,O'Shea, Donal F.
, p. 7836 - 7846 (2007/10/03)
An effective synthesis of the functionalized indole ring system has been developed from substituted o-aminostyrene starting material. Our methodology involves a novel cascade reaction sequence of alkyllithium addition to the styrene double bond and subsequent trapping of the intermediate organolithium with a suitable electrophile, followed by an in situ ring closure and dehydration to generate the indole ring. This new reaction sequence allows for the introduction of molecular diversity at all positions on the indole scaffold. The procedure was shown to be successful with a range of both C and N substituents on the o-aminostyrenes. The reaction sequence was tolerant to the reactivity range of alkyllithiums such as tert-, sec-, and n-butyllithium. The electrophiles used were DMF, which generated indole products with C-2 unsubstituted, and nitriles, which incorporated the nitrile substituent at C-2. The o-aminostyrene starting materials were generated by a Pd-catalyzed cross-coupling reaction of a vinyl boronic acid equivalent with the readily available substituted o-bromoanilines.
Ortho-Vinylation reaction of anilines
Yamaguchi, Masahiko,Arisawa, Mieko,Hirama, Masahiro
, p. 1399 - 1400 (2007/10/03)
N-Alkylanilines and anilines are vinylated at the ortho-position with ethyne in the presence of SnCl4-Bu3N.
