1,3-Diphenylbenzo[e][1,2,4]triazin-7(1H)-one: selected chemistry at the C-6, C-7 and C-8 positions

1,3-Diphenylbenzo[e][1,2,4]triazin-7(1H)-one (6) reacts with tetracyanoethylene (TCNE) or tetracyanoethylene oxide (TCNEO) to give the deep green 2-[1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-ylidene]propanedinitrile (11) in 17 and 15% yields, respectively. Nucleophiles such as amines, alkoxides, thiols and Grignard reagents all reacted with the 1,3-diphenylbenzotriazinone 6 regioselectively at C-6, while halogenating agents reacted exclusively at C-8. Furthermore, 8-iodo-1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (32) undergoes palladium-catalysed Suzuki-Miyaura and Stille coupling reactions to give 8-aryl- or heteroaryl-substituted benzotriazinones. By combining both the C-6 and C-8 chemistries 1,3,6,8-tetraphenylbenzo[e][1,2,4]triazin-7(1H)-one (42) and 1,3-diphenyl-6,8-di(thien-2-yl)-benzo[e][1,2,4]triazin-7(1H)-one (43) can be prepared. All new compounds are fully characterized.     

Double electron-nuclear resonance of free radical 1,3-diphenyl-1, 4-dihydro-1,2,4-benzotriazin-4-yl

Conclusions The HFS constants for the protons in positions 5–13 of the free radical 1,3-diphenyl-1, 4-dihydro-1,2,4-benzotriazin-4-yl were determined by the DENR method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 698–699, March, 1984.     

Tandem Stille/Suzuki-Miyaura coupling of a hetero-bis-metalated diene. Rapid, one-pot assembly of polyene systems

[structure: see text]. The synthesis of a hetero-bis-metallo 1,3-butadiene is reported, and its use as an orthogonal Stille and Suzuki-Miyaura coupling partner is detailed. The tin/boron diene participated successfully in a one-pot, sequential Stille and Suzuki-Miyaura coupling protocol, and its utility was demonstrated in the two-step construction of the pentaene side chain of the Fusarium metabolite lucilactaene.     

Some cyclization reactions of 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one: preparation and computational analysis of non symmetrical zwitterionic biscyanines

Regioselective nucleophilic addition of bisnucleophiles 1,2-benzenediamine, 2-amino-benzenethiol, and N-phenyl-1,2-benzenediamine to 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (1) at C6 followed by intramolecular cyclocondensation at the C7 carbonyl afforded highly coloured tetracenes 1,3-diphenyl-1,6-dihydro-[1,2,4]triazino[5,6-b]phenazin-4-ium 4-methylbenzenesulfonate (12), 1,3-diphenyl-1H-[1,2,4]triazino[6,5-b]phenothiazine (14) and 1,3,11-triphenyl-1,6-dihydro-[1,2,4]triazino[5,6-b]phenazin-11-ium 4-methylbenzenesulfonate (15), respectively. Neutralization of the latter with alkali gave the free base 1,3,11-triphenyl-1H-[1,2,4]triazino[5,6-b]phenazin-11-ium-6-ide (16). Furthermore, the benzotriazinone 1 reacts with dimethyl malonate to give 6-(methoxycarbonyl)-7-oxo-1,3-diphenyl-7H-benzofuro[5,6-e][1,2,4]triazin-1-ium-4-ide (17) in 74% yield, while with S(4)N(4) [5,6-c]-thiadiazolo-7-oxo-1,3-diphenyl-1,2,4-benzotriazine (22) was formed in 15% yield. The free bases 16 and 17 display negative solvatochromism, which supports charge separated ground states similar to those of zwitterionic biscyanines, and DFT calculations at the UB3LYP/6-31G(d) level afford ΔE(ST) values of -13.6 and -18.7 kcal mol(-1), respectively that strongly favour the singlet ground state. All ring systems described are new and fully characterized.     

Organosulfur compounds: electrophilic reagents in transition-metal-catalyzed carbon-carbon bond-forming reactions

Transition-metal-catalyzed carbon-carbon bond-forming reactions are among the most powerful methods in organic synthesis and play a crucial role in modern materials science and medicinal chemistry. Recent developments in the area of ligands and additives permit the cross-coupling of a large variety of reactants, including inexpensive and readily available sulfonyl chlorides. Their desulfitative carbon-carbon cross-coupling reactions (Negishi, Stille, carbonylative Stille, Suzuki-Miyaura, and Sonogashira-Hagihara-type cross-couplings and Mizoroki-Heck-type arylations) are reviewed together with carbon-carbon cross-coupling reactions with other organosulfur compounds as electrophilic reagents.     

Ferromagnetic interactions in a 1D alternating linear chain of π-stacked 1,3-diphenyl-7-(thien-2-yl)-1,4-dihydro-1,2,4-benzotriazin-4-yl radicals

X-ray studies show that 1,3-diphenyl-7-(thien-2-yl)-1,4-dihydro-1,2,4-benzotriazin-4-yl (6) adopts a distorted, slipped π-stacked structure of centrosymmetric dimers with alternate short and long interplanar distances (3.48 and 3.52 ?). Cyclic voltammograms of 7-(thien-2-yl)benzotriazin-4-yl 6 show two fully reversible waves that correspond to the -1/0 and 0/+1 processes. EPR and DFT studies on radical 6 indicate that the spin density is mainly delocalized over the triazinyl fragment. Magnetic susceptibility measurements show that radical 6 obeys Curie-Weiss behavior in the 5-300 K region with C=0.378 emu K mol(-1) and θ=+4.72 K, which is consistent with ferromagnetic interactions between S=1/2 radicals. Fitting the magnetic susceptibility revealed the behavior is consistent with an alternating ferromagnetic chain (g=2.0071, J(1) =+7.12 cm(-1), J(2) =+1.28 cm(-1)).     

The bromopentadienyl acrylate approach to himbacine

[reaction: see text] The syntheses of 4,4a-didehydrohimbacine and 4,4a-didehydrohimandravine are presented. Key steps include an intramolecular Diels-Alder reaction of a bromopentadienyl acrylate and Suzuki-Miyaura and Stille coupling reactions.     

Phosphinates as new electrophilic partners for cross-coupling reactions

The use of enol phosphinates as electrophiles for cross-coupling reactions has been explored. Both boronic acids (Suzuki-Miyaura reaction) and stannanes (Stille reaction) couple efficiently with lactam derived phosphinates.     

PEG-400 promoted Pd(OAc)2/DABCO-catalyzed cross-coupling reactions in aqueous media

PEG-400 [poly(ethylene glycol-400)] was found to improve the Pd(OAc)₂/DABCO-catalyzed aqueous Suzuki-Miyaura and Stille cross-coupling reactions. In the presence of Pd(OAc)₂, DABCO, and PEG-400, a variety of aryl halides were coupled with arylboronic acids or organotin compounds efficiently to afford the corresponding cross-coupled products in moderate to excellent yields. The turnover numbers was up to 900,000 for the Suzuki-Miyaura reaction and up to 9800 for the Stille reaction. The catalyst system was also effective for Heck and Sonogashira cross-coupling reactions to some extent.     

Palladium catalyzed C-C coupling reactions of 3,5-dichloro-4H-1,2,6-thiadiazin-4-one

Palladium catalyzed Suzuki-Miyaura, Stille, and Sonogashira coupling reactions are reported for the electron-deficient heterocyclic scaffold 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (1). Furthermore, 3,5-di(thien-2-yl)-4H-1,2,6-thiadiazin-4-one (7m) is further elaborated to afford the tetrathienyl 3,5-bis[(2,2'-bithien)-5-yl]-4H-1,2,6-thiadiazin-4-one (9). All compounds are fully characterized.     

Total synthesis of lucilactaene, a cell cycle inhibitor active in p53-inactive cells

Hetero-bis-metalated 1,3-butadiene is employed in the lynchpin coupling of synthetic fragments of the side chain of the antitumor agent, lucilactaene. Sequential Stille and Suzuki-Miyaura couplings interpolate this unique boron/tin diene into the pentaene chain. The total synthesis of lucilactaene was accomplished efficiently, in just eight linear steps.     

Enol tosylates as viable partners in Pd-catalyzed cross-coupling reactions

[reaction: see text] Herein we demonstrate functionalized enol tosylates to be robust substrates that undergo Suzuki-Miyaura, Sonogashira, and Stille cross-coupling reactions to provide stereodefined trisubstituted unsaturated esters.     

Highly convergent, stereospecific synthesis of 11-cis-retinoids by metal-catalyzed cross-coupling reactions of (Z)-1-alkenylmetals

A stereospecific synthesis of 11-cis-retinoids has as its key step the hitherto unexplored palladium-catalyzed cross-coupling of trans-trienyl electrophiles and (1Z,3E)-penta-1,3-dienyl boronates (a Suzuki-Miyaura reaction) or stannanes (a Stille reaction). This highly convergent approach constitutes the first application of cis-organometallic moieties to the synthesis of 11-cis-retinoids and represents a general, straightforward route to the visual chromophore.     

Oxime palladacycles revisited: stone-stable complexes nonetheless very active catalysts

Our review critically presents the main achievements, advantages, and limitations of oxime palladacycles as high-turnover catalysts for Heck, as well as homo- and cross-coupling reactions such as Suzuki-Miyaura, Stille, Ullmann-type, Cassar-Heck-Sonogashira, sila-Sonogashira, Glaser-type, Hiyama, and alkoxycarbonylation reactions. New developments in this area are reviewed from a mechanistic and synthetic point of view. The role of oxime palladacycles as a source of highly active zero-valent palladium species is also discussed.     

新型含三唑的烯丙基苯甲酸酯类化合物的合成及杀菌活性研究

为了寻找高杀菌活性的农药先导化合物,设计合成了一系列未见文献报道的含三唑的烯丙基苯甲酸酯类化合物,其结构经1H NMR和HRMS进行了确证,用X射线单晶衍射测定了(R,S)-(Z)-1,3-二苯基-2-(1H-1,2,4-三唑-1-基)烯丙基2,3-二氯苯甲酸酯(5j)的晶体结构.生物活性测定结果表明,在50 mg/L的浓度下,(R,S)-(Z)-1,3-二苯基-2-(1H-1,2,4-三唑-1-基)烯丙基苯甲酸酯(5a),(R,S)-(Z)-1,3-二苯基-2-(1H-1,2,4-三唑-1-基)烯丙基2-氟苯甲酸酯(5g)和(R,S)-(Z)-1,3-二苯基-2-(1H-1,2,4-三唑-1-基)烯丙基3-甲基苯甲酸酯(5n)对油菜菌核的抑菌率均达到了70%以上,显示出了较高的杀菌活性.     

Preparation and cycloaddition reactions of enantiopure 2-(N-acylamino)-1,3-dienes for the synthesis of octahydroquinoline derivatives

Stille, Suzuki-Miyaura, and Sonogashira cross-coupling reactions were carried out with a glutarimide-derived vinyl phosphate, bearing a chiral auxiliary on the N atom, to prepare enantiopure 2-(N-acylamino)-1,3-dienes as partners in Diels-Alder reactions. The cycloadditions were performed with various dienophiles under thermal conditions, with or without Lewis acids. With maleimides, the preferential formation of endo cycloadducts was observed, whereas with acrylamides the exo approach prevailed. Furthermore, in the latter case, 6-substitued octahydroquinolinones were obtained in accordance with the predicted regioselectivity. Since diastereopure compounds were in all cases obtained either by chromatography or by crystallization, and because of the easy access to a variety of boronic acids, to be used in the coupling step, this methodology is useful for the short synthesis of differently substituted, enantiopure octahydroquinolinones amenable to further transformation into decahydroquinolines possessing interesting biological activities.     

胺作为配体在钯催化偶联反应中应用

对近期我们研究小组及其它研究小组在利用胺作为钯催化偶联反应的配体研究进展进行了总结. 钯/胺作为催化体系主要应用的偶联反应包括: Suzuki-Miyaura交叉反应, Sonogashira交叉反应, Stille交叉反应, Hiyama交叉反应和Heck反应. 研究结果表明胺可以作为价廉和高效的配体促进钯催化交叉偶联反应.     

Triazole-based monophosphine ligands for palladium-catalyzed cross-coupling reactions of aryl chlorides

A variety of triazole-based monophosphines (ClickPhos) have been prepared via efficient 1,3-dipolar cycloaddition of readily available azides and acetylenes. Their palladium complexes provided excellent yields in the amination reactions and Suzuki-Miyaura coupling reactions of unactivated aryl chlorides. Ligand 7i, which has a 2,6-dimethoxybenzene moiety, provided good results in Suzuki-Miyaura reaction to form hindered biaryls. A CAChe model for the Pd/7i complex shows that the likelihood of a Pd-arene interaction might be a rationale for its high catalytic reactivity.     

A guideline for the arylation of positions 4 and 5 of thiazole via Pd-catalyzed cross-coupling reactions

The arylation of thiazoles in 4- and 5-position was investigated in detail. Suzuki-Miyaura and Stille cross-coupling reactions were tested using thiazoles either as halide or organometal species. The obtained results were critically compared to develop helpful guidelines for selection of the cross-coupling methodology with the best potential for good and reliable results for a given synthetic problem without the need for tedious optimization of reaction parameters.     

Molecular and Crystal Structure of a Superstable Free Radical, 1,3-Diphenyl-1,4-dihydro-1,2,4-benzotriazin-4-yl

The molecular and crystal structure of a superstable free radical, 1,3-diphenyl-1,4-dihydro-1,2,4-benzotriazin-4-yl, was studied by single crystal X-ray diffraction. The dihedral angle formed by the N-phenyl ring with the heteroring is considerably larger than that formed by the C-phenyl ring; two geminal C-N bonds in the dihydrotriazine ring have virtually equal length. In the crystal, the radical molecules form stacks along the 0b axis due to - interactions of the aromatic fragments of the molecules. The total effect of intermolecular contacts in the crystal leads to formation of a lamellar supramolecular structure.