cas 1730-48-9, 6-METHOXY-1,2,3,4-TETRAHYDRONAPHTHALENE

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Eckhard,I.F. et al.
p. 2493 - 2497
(1970)
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Experimental investigation of excited state electron transfer reactions between some bicyclic molecules and tetracyanoquinodimethane (TCNQ)
Investigations on photoinduced electron transfer (ET) reactions between excited (ground) bicyclic electron donors 5,6,7,8-tetrahydro-2-naphthol (TH2N), 2-methoxy-5,6,7,8-tetrahydro naphthalene (2MTHN) and ground state (excited) acceptor tetracyanoquinodimethane (TCNQ) in fluid solutions of different polarity at the ambient temperature (300 K) by electronic absorption, steady state fluorescence and time-resolved spectroscopic methods in the time domain of nanosecond order have been carried out.It is suggested that in highly polar solvent acetonitrile (ACN), a loosely-structured transient geminate ion-pair complex (GIP) in the excited singlet state (S1) is formed due to the ET encounter between the present donor TH2N or 2MTHN and TCNQ and this GIP complex rapidly dissociates into stable excited radical ions, as evidenced from steady state spectra.In polar DMF solvents, TCNQ exhibits an electronic absorption band of its anion without the presence of donor molecules.Both steady state and time-resolved data indicate that ET reactions between the present donors and acceptor TCNQ are largely impeded in the less polar solvent tetrahydrofuran (THF).In the highly polar solvent ACN, ET reactions between the donors and acceptor TCNQ have been suggested to be of adiabatic or intermediate between adiabatic and non-adiabatic types, from the observation of radical ion species in the electronic excited state.For some bicyclic donors and TCNQ acceptor systems, large negative ΔG, which is a measure of the gap between locally excited and radical ion-pair states, shows reaction occurs in highly exothermic regions.Further observations of -Δ>λ, nuclear reorganization energy parameters and the decrement of ET rate (kET) with increasing exothermicity (more negative Δ values) suggest the ET reaction for the bicyclic donor-TCNQ acceptor systems studied in the present investigation might occur in the Marcus inverted region.The possibility of building up efficient photoconducting materials with the present donor acceptor systems is suggested.
De, R.,Bhattacharyya, S.,Ganguly, T.
p. 2155 - 2166
(1994)
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Synthesis of decaline analogues of isovelleral
Decaline analogues of the bioactive fungal sesquiterpene (+)-isovelleral (1a), retaining the bicyclo[4,1,0]hept-2-en-1,2-dicarbaldehyde system, were prepared, and their cytotoxic and antimicrobial activities were compared with those of the natural product. While the two isomers (±)-2 and (±)-3 were as active as isovelleral (1a), the isomer (±)-4 was approximately 10 times less potent.
Johansson,Aujard,R?me,Anke,Sterner
p. 984 - 989
(2005)
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Non-radiative depletion of the excited electronic states of 9-cyanoanthracene in presence of tetrahydronaphthols.
Both steady state and time resolved spectroscopic measurements reveal that the prime process involved in quenching mechanism of the lowest excited singlet (S1) and triplet (T1) states of the well known electron acceptor 9-Cyanoanthracene (9CNA) in presence of 5,6,7,8-tetrahydro-1-naphthol (TH1N) or 5,6,7,8-tetrahydro-2-naphthol (TH2N) is H-bonding interaction. It has been confirmed that the fluorescence of 9CNA is not at all affected in presence of 5,6,7,8-tetrahydro-2-methoxy naphthalene (TH2MN) both in non-polar n-heptane (NH) and highly polar acetonitrile (ACN) media. This indicates that the H-bonding interaction is crucial for the occurrence of the quenching phenomenon observed in the present investigations with TH1N (or TH2N) donors and 9CNA acceptor. In ACN solvent both contact ion-pair (CIP) and solvent-separated (or dissociated) ions are formed due to intermolecular H-bonding interactions in the excited electronic states (both singlet and triplet). In NH environment due to stronger H-bonding interactions, the large proton shift within excited charge transfer (CT) or ion-pair complex, 1 or 3(D+-H...A-), causes the formation of the neutral radical, 3(D+H-A)*, due to the complete detachment of the H-atom. It is hinted that both TH1N and TH2N due to their excellent H-bonding ability could be used as antioxidants.
Bhattacharya,Misra,Maiti,Saini,Chanda,Lahiri,Ganguly
p. 525 - 535
(2003)
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Catalytic Transfer Hydrogenation of Arenes and Heteroarenes
Transfer hydrogenation reactions are of great interest to reduce diverse molecules under mild reaction conditions. To date, this type of reaction has only been successfully applied to alkenes, alkynes and polarized unsaturated compounds such as ketones, imines, pyridines, etc. The reduction of benzene derivatives by transfer hydrogenation has never been described, which is likely due to the high energy barrier required to dearomatize these compounds. In this context, we have developed a catalytic transfer hydrogenation reaction for the reduction of benzene derivatives and heteroarenes to form complex 3-dimensional scaffolds bearing various functional groups at room temperature without needing compressed hydrogen gas.
Gelis, Coralie,Heusler, Arne,Nairoukh, Zackaria,Glorius, Frank
supporting information
p. 14090 - 14094
(2020/10/19)

Multistep Synthesis and in Vitro Anticancer Evaluation of 2-Pyrazolyl-Estradiol Derivatives, Pyrazolocoumarin-Estradiol Hybrids and Analogous Compounds
Although the hormone independent cytotoxic activity of several estradiol derivatives endowed with a simple substituent at C-2 has been reported so far, 2-heterocyclic and 2,3-condensed analogs are less investigated from both synthetic and pharmacological points of view. Therefore, novel A-ring-connected 2-pyrazoles of estradiol and, for comparison, their structurally simplified non-steroidal pairs were synthesized from estradiol 3-methyl ether and 6-methoxy-1,2,3,4-tetrahydronaphthalene. Friedel-Crafts acetylation of the protected phenolic compounds and subsequent O-demethylation led to ortho-substituted derivatives regioselectively, which were converted to arylhydrazones with phenylhydrazine, 4-tolylhydrazine and 4-chloro-phenylhydrazine, respectively, under microwave conditions. The hydrazones were subjected to cyclization with the Vilsmeier-Haack reagent immediately after preparation and the ring closure/formylation sequence resulted in steroidal and non-steroidal 40-formylpyrazoles in moderate to good yields. During reductive transformations, 4-hydroxymethyl-pyrazoles were obtained, while oxidative lactonization of the 4-formylpyrazole moiety with the phenolic OH in the presence of the Jones reagent afforded A-ring-integrated pyrazolocoumarin hybrids and related analogs. Steroidal pyrazoles, which were produced as C-17 acetates due to acetylation of C-17 OH during the primary Friedel-Crafts reaction, underwent deacetylation in alkaline methanol to furnish 2-heterocyclic estradiol derivatives. Pharmacological studies revealed the overall and cancer cell-specific cytotoxicity of the derivatives and the half maximal inhibitory concentrations were obtained for the most promising compounds.
Adamecz, Dóra Izabella,Frank, éva,Kiricsi, Mónika,Krishna Gopisetty, Mohana,Molnár, Barnabás
(2020/09/18)

Mild and efficient rhodium-catalyzed deoxygenation of ketones to alkanes
A new and simple method for the deoxygenation of ketones to alkanes is presented. Most substrates are reduced under mild conditions by triethylsilane in the presence of catalytic amounts of [Rh(μ-Cl)(CO)2]2. This system selectively provides the methylene hydrocarbons in good to excellent yields starting from acetophenones and diaryl ketones. A rapid examination of the reaction pathway suggests that the ketone is first converted into an alcohol, which then undergoes hydrogenolysis to give the alkane.
Argouarch, Gilles
supporting information
p. 11041 - 11044
(2019/07/31)

Scalable Wolff-Kishner Reductions in Extreme Process Windows Using a Silicon Carbide Flow Reactor
A safe and scalable continuous flow strategy for Wolff-Kishner reductions that employs methanol as the solvent has been developed. The use of low-cost hydrazine as the reducing agent in combination with a caustic base provides an atom-efficient, environmentally friendly method for the deoxygenation of aldehydes and ketones to alkanes. Because of the required harsh and corrosive reaction conditions (200 °C, 50 bar), reactor materials such as stainless steel, glass, or any type of polymer have compatibility problems, rendering this process problematic on a production scale. The use of corrosion-resistant silicon carbide (SiC) as the reactor material opens up the possibility of performing Wolff-Kishner reductions on scale with a considerably improved safety profile. Methanol as the solvent significantly simplifies the workup procedure compared with the generally employed high-boiling solvents such as diethylene glycol. The continuous flow protocol was applied to a number of substrates and provided the desired products in good to high yields with space-time yields of up to 152 g L-1 h-1. In addition, a pharmaceutically valuable active pharmaceutical ingredient precursor was synthesized by employing this higherature/pressure Wolff-Kishner protocol.
Znidar, Desiree,O'Kearney-Mcmullan, Anne,Munday, Rachel,Wiles, Charlotte,Poechlauer, Peter,Schmoelzer, Christoph,Dallinger, Doris,Kappe, C. Oliver
p. 2445 - 2455
(2019/11/03)

Rapid probing of the reactivity of P450 monooxygenases from the CYP116B subfamily using a substrate-based method
Developing a detailed understanding of the reactivity of self-sufficient Type IV P450 monooxygenases, four types of O-methylated substrates were designed as probes, including monoterpenes, cycloalkanes, aromatic compounds and steroids, and the efficiency of their oxyfunction was determined using a colorimetric assay which was based on the reaction between the enzymatic demethylation product, formaldehyde, and Purpald dye. The activity-based fingerprints of new P450RpMO, P450ArMO and P450CtMO (CYP116B members) indicated that CYP116B P450s preferentially oxidize substrates with aromatic components. Moreover, the hydroxylated products were detected based on the preference results. This rapid and efficient strategy, when coupled with GCMS, enables the exploration of the reactivity of other CYP116B members.
Li, Ren-Jie,Xu, Jian-He,Yin, Yue-Cai,Wirth, Nicolas,Ren, Jiang-Meng,Zeng, Bu-Bing,Yu, Hui-Lei
supporting information
p. 8928 - 8934
(2016/10/13)

Selective catalytic hydrogenation of polycyclic aromatic hydrocarbons promoted by ruthenium nanoparticles
Ru nanoparticles stabilised by PPh3 are efficient catalysts for hydrogenation of polycyclic aromatic hydrocarbons (PAHs) containing 2-4 rings under mild reaction conditions. These compounds were partially hydrogenated with good to excellent selectivities just by optimizing the reaction conditions. The influence of the nature of substituents present in different positions of naphthalene on the selectivity of hydrogenation was also studied. Hydrogenation of products containing substituents at position 1 is slower than that of products containing substituents at position 2. In all cases, hydrogenation takes place mainly on the less substituted ring.
Bresó-Femenia, Emma,Chaudret, Bruno,Castillón, Sergio
p. 2741 - 2751
(2015/05/27)

Scope and Mechanistic Analysis for Chemoselective Hydrogenolysis of Carbonyl Compounds Catalyzed by a Cationic Ruthenium Hydride Complex with a Tunable Phenol Ligand
A cationic ruthenium hydride complex, [(C6H6)(PCy3)(CO)RuH]+BF4- (1), with a phenol ligand was found to exhibit high catalytic activity for the hydrogenolysis of carbonyl compounds to yield the corresponding aliphatic products. The catalytic method showed exceptionally high chemoselectivity toward the carbonyl reduction over alkene hydrogenation. Kinetic and spectroscopic studies revealed a strong electronic influence of the phenol ligand on the catalyst activity. The Hammett plot of the hydrogenolysis of 4-methoxyacetophenone displayed two opposite linear slopes for the catalytic system 1/p-X-C6H4OH (ρ = -3.3 for X = OMe, t-Bu, Et, and Me; ρ = +1.5 for X = F, Cl, and CF3). A normal deuterium isotope effect was observed for the hydrogenolysis reaction catalyzed by 1/p-X-C6H4OH with an electron-releasing group (kH/kD = 1.7-2.5; X = OMe, Et), whereas an inverse isotope effect was measured for 1/p-X-C6H4OH with an electron-withdrawing group (kH/kD = 0.6-0.7; X = Cl, CF3). The empirical rate law was determined from the hydrogenolysis of 4-methoxyacetophenone: rate = kobsd[Ru][ketone][H2]-1 for the reaction catalyzed by 1/p-OMe-C6H4OH, and rate = kobsd[Ru][ketone][H2]0 for the reaction catalyzed by 1/p-CF3-C6H4OH. Catalytically relevant dinuclear ruthenium hydride and hydroxo complexes were synthesized, and their structures were established by X-ray crystallography. Two distinct mechanistic pathways are presented for the hydrogenolysis reaction on the basis of these kinetic and spectroscopic data. (Chemical Equation Presented).
Kalutharage, Nishantha,Yi, Chae S.
supporting information
p. 11105 - 11114
(2015/09/15)

Dioxomolybdenum Complexes as Excellent Catalysts for the Deoxygenation of Aryl Ketones to Aryl Alkenes
This work describes a new methodology for the selective deoxygenation of aryl ketones to the corresponding aryl alkenes catalyzed by dioxomolybdenum complexes using silanes as reducing agents. The best results were obtained with the system PhSiH3/MoO2Cl2(H2O)2 (5-10 mol %), which was very efficient for the deoxygenation of a large variety of aryl ketones to alkenes in excellent yields. This new methodology has the advantages of using an inexpensive, environmentally friendly, easily prepared, and air-stable catalyst in ether solution.
Fernandes, Tiago A.,Fernandes, Ana C.
p. 3503 - 3507
(2015/11/10)

Efficient palladium-catalyzed C-O hydrogenolysis of benzylic alcohols and aromatic ketones with polymethylhydrosiloxane
A simple method has been developed for the reductive deoxygenation of aromatic ketones and benzylic alcohols in the presence of polymethylhydrosiloxane (PMHS). The reductive deoxygenation of aromatic ketones and benzylic alcohols, including secondary alcohols, to the corresponding methylene hydrocarbons has been achieved in good to excellent yields using palladium chloride (PdCl2) as catalyst and PMHS as hydride source. Such deoxygenations were successfully with aryl alkyl ketones and diaryl ketones, as exemplified by the reductive deoxygenation of acetophenone and benzopheneone, respectively. The corresponding benzylic alcohols and secondary alcohol analogues could also be converted into their respective methylene hydrocarbons by the PdCl2/PMHS system.
Wang, Hu,Li, Li,Bai, Xing-Feng,Shang, Jun-Yan,Yang, Ke-Fang,Xu, Li-Wen
supporting information
p. 341 - 347
(2013/05/08)

One-by-one hydrogenation, cross-coupling reaction, and Knoevenagel condensations catalyzed by PdCl2 and the downstream palladium residue
A novel catalyst-economic strategy with a recovered palladium catalyst was successfully applied for multi-task and maximum reuse in different types of one-by-one downstream reactions, from catalytic hydrogenation to Suzuki and Sonogashira-type cross-coupling reactions, Knoevenagel condensations, and trans-Knoevenagel-like condensations.
Wang, Hu,Li, Li,Bai, Xing-Feng,Deng, Wen-Hui,Zheng, Zhan-Jiang,Yang, Ke-Fang,Xu, Li-Wen
supporting information
p. 2349 - 2355
(2013/09/12)

Copper-catalyzed alkene arylation with diaryliodonium salts
Alkenes and arenes represent two classes of feedstock compounds whose union has fundamental importance to synthetic organic chemistry. We report a new approach to alkene arylation using diaryliodonium salts and Cu catalysis. Using a range of simple alkenes, we have shown that the product outcomes differ significantly from those commonly obtained by the Heck reaction. We have used these insights to develop a number of new tandem and cascade reactions that transform readily available alkenes into complex arylated products that may have broad applications in chemical synthesis.
Phipps, Robert J.,McMurray, Lindsay,Ritter, Stefanie,Duong, Hung A.,Gaunt, Matthew J.
supporting information; experimental part
p. 10773 - 10776
(2012/08/07)

1-Chloro-2-formyl indenes and tetralenes as antitubercular agents
1-Chloro-2-formyl indenes and tetralenes have been synthesized using Vilsmeier-Haack-Arnold reaction onto indanones and tetralones. Most of these analogues exhibited antitubercular activity against Mycobacterium tuberculosis H37Rv strain with MICs ranging from 30 to 500 μg/mL. Analogue 13 was further modified to some derivatives. The most active analogue 23 showing MIC at 30 μg/mL was further evaluated for acute oral toxicity in Swiss albino mice and was found to be safe up to 300 mg/kg dose.
Chanda, Debabrata,Saikia, Dharmendra,Kumar,Thakur, Jay Prakash,Agarwal, Jyoti,Chanotiya,Shanker, Karuna,Negi, Arvind S.
scheme or table
p. 3966 - 3969
(2011/08/06)

A benzannulation protocol to prepare substituted aryl amines using a michael-aldol reaction of β-keto sulfones
(Chemical Equation Presented) A practical benzannulation method to prepare variously substituted aryl amines and sulfides was developed. The approach involves a Michael-aldol reaction of β-keto sulfones with enones followed by a subsequent condensation of the initial adduct with various amines. The base-induced Michaelaldol cascade proceeds smoothly with a number of different β-keto sulfones, affording the adducts as single diastereomers. Heating the resulting Michael-aldol product with an amine in toluene at 120°C results in the formation of a transient enamine, which then undergoes loss of phenyl sulfenic acid to furnish the aromatized amine in good yield. A related reaction also occurred when the Michael-aldol product was heated with thiols or alcohols, giving rise to aryl-substituted sulfides or ethers.
Kiren, Sezgin,Padwa, Albert
experimental part
p. 7781 - 7789
(2009/12/30)

Gold-catalyzed substitution reaction with ortho-alkynylbenzoic acid alkyl ester as an efficient alkylating agent
ortho-Alkynylbenzoic acid alkyl esters behave as alkylating agents in combination with gold catalysts. The reaction with alcohols occurs smoothly in the presence of catalytic amounts of Ph3PAuCl and AgOTf under mild conditions to produce the corresponding ether products in high yields. The protocol is also useful for Friedel-Crafts alkylation and N-alkylation of sulfonamides. The reaction likely proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack of nucleophiles, such as alcohols, aromatic compounds, and sulfonamides.
Aikawa, Haruo,Tago, Sakie,Umetsu, Kazuteru,Haginiwa, Naomichi,Asao, Naoki
experimental part
p. 1774 - 1784
(2009/06/20)

Commercially available liquid enol ethers and acetates as gaseous alkyne equivalents in cationic Rh(I)/BINAP-catalyzed chemo- and regioselective formal cross-alkyne cyclotrimerizations
A cationic rhodium(I)/BINAP complex catalyzes partial intramolecular [2+2+2] cycloadditions of 1,6- and 1,7-diynes with enol ethers or a ketene acetal giving substituted benzenes in good yields. The same catalyst also catalyzes complete intermolecular [2+
Hara, Hiromi,Hirano, Masao,Tanaka, Ken
scheme or table
p. 5093 - 5101
(2009/12/01)

Rhodium and iridium nanoparticles entrapped in aluminum oxyhydroxide nanofibers: Catalysts for hydrogenations of arenes and ketones at room temperature with hydrogen balloon
The recyclable metal nanoparticle catalysts, rhodium in aluminum oxyhydroxide [Rh/ AlO(OH)] and iridium in aluminum oxyhydroxide [Ir/A1O(OH)], were simply prepared from readily available reagents. The catalysts showed high activities in the hydrogenation of various arenes and ketones under mild conditions. Selective hydrogenation was possible for bicyclic and tricyclic arenes in high yields. The catalysts were active at room temperature even with a hydrogen balloon. Also, the catalysts showed high turnover frequency (TOF) values under solventless conditions at 75 °C under 4 atm hydrogen pressure: ca. 1700h 1 in the hydrogenation of benzene. Furthermore, Rh/A1O(OH) can be reused forat least 10 times without activity loss. The catalysts were characterized by the transmission electron microscopy (TEM), powder X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and hydrogen chemisorption experiments. The sizes of rhodium and iridium particles were estimated to be 3-4 nm and 2-3 nm, respectively. Aluminum oxyhydroxide nanofibers of these catalysts have surface areas of 500-600 m2 g -1.
Park, In Soo,Kwon, Min Serk,Kang, Kyung Yeon,Lee, Jae Sung,Park, Jaiwook
p. 2039 - 2047
(2008/09/17)

Gold-catalyzed etherification and friedel - Crafts alkylation using ortho-alkynylbenzoic acid alkyl ester as an efficient alkylating agent
A gold-catalyzed alkylation of alcohols and aromatic compounds is described. The reaction of ortho-alkynylbenzoic acid alkyl esters with alcohols or aromatic compounds occurs in the presence of catalytic amounts of Ph 3PAuCl and AgOTf under mild conditions to produce corresponding ethers or Friedel-Crafts alkylation products in good to high yields. The reaction likely proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack of alcohols or aromatic compounds.
Asao, Naoki,Aikawa, Haruo,Tago, Sakie,Umetsu, Kazuteru
p. 4299 - 4302
(2008/02/12)

Preparation and application of odorless 1,3-propanedithiol reagents
2-Dodecyl-1,3-propanedithiol (2a) was prepared without a malodorous procedure as an odorless reagent that was usable in place of 1,3-propanedithiol (1) in organic reactions, e.g., in the reduction of azides and protection of carbonyl groups. The 1,3-dithioacetals obtained in the latter reaction were effectively reduced to methylene with Raney nickel and reconverted to the original carbonyl compounds by hydrolysis with N-bromosuccinimide in aqueous 2-butanone. In addition, the anion of 1,3-dithiane prepared from 2a and formaldehyde could be utilized as a synthetic equivalent of an anionic carbonyl carbon.
Matoba, Manabu,Kajimoto, Tetsuya,Nishide, Kiyoharu,Node, Manabu
p. 141 - 146
(2007/10/03)

Regioselective synthesis of 2,6-dimethyltetralin: Key precursor to 2,6-dimethylnaphthalene
A novel regioselective synthesis for 2,6-dimethyltetralin (2,6-DMT), a key precursor to 2,6-dimethylnaphthalene (2,6-DMN), is described. The synthesis comprises the following three steps; the Heck reaction between commercially available 4-bromotoluene and 3-methyl-3-buten-1-ol, the catalytic reduction of the coupling products, and the acid-catalyzed cyclization of the alcohol intermediate. The process has an advantage over the established processes in that 2,6-DMT is obtained as the only isomer, and the isomerization and/or the complicated separation and purification steps are not required to produce pure 2,6-DMT. 2,6-DMN could be also obtained as a major product depending on the cyclization conditions.
Byung, Hyun Kim,Jong, Gil Lee,Woon, Ki Kim,Young, Gyu Kim
p. 814 - 817
(2012/12/26)

Recoverable, Reusable, Highly Active, and Sulfur-Tolerant Polymer Incarcerated Palladium for Hydrogenation
A new type of immobilized palladium, PI (polymer incarcerated) Pd (2b), from Pd(PPh3)4 and copolymer (1b) has been developed. The excellent activity of PI Pd has been demonstrated in hydrogenation of various olefins, benzyl ethers, and nitro and aromatic compounds. PI Pd is tolerant under high pressure and high temperature and can be recovered and reused several times without loss of activity even under harsh conditions. Moreover, PI Pd is highly resistant to poisoning by sulfur.
Okamoto, Kuniaki,Akiyama, Ryo,Kobayashi, Shu
p. 2871 - 2873
(2007/10/03)

SUBSTITUTED PYRAZINE DERIVATIVES
The present invention provides substituted pyrazine derivatives of Formula (I), that are CRF1 receptor antagonists, including human CRF1 receptors. This invention also relates to use of compounds of the invention for treating a disorder or condition, the treatment of which can be effected or facilitated by antagonizing a CRF receptor, such as CNS disorders, particularly anxiety-related disorders and mood disorders.
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Page/Page column 56-57

(2010/02/07)

The Huang-Minlon modification of Wolff-Kishner reduction in rapid and simple way using microwave technology
A high yielding, simple and fast method for the reduction of various aldehydes and ketones to the respective hydrocarbons following Huang-Minlon modification tender microwave irradiation is described.
Chattopadhyay, Sarmishtha,Banerjee, Sajal Kumar,Mitra, Alok Kumar
p. 906 - 907
(2007/10/03)

1,3-Benzodithiolium Cation Mediated Cyclization Reactions
General protocols for the construction of various ring systems employing cation olefin cyclizations initiated by the readily accessible 1,3-benzodithiolium ion are described.Several substituted tetralones and tetralins can be rapidly assembled by this methodology as can a variety of substituted bicyclooctane and tricyclic ring systems.The products of these transformations are amenable to interconversion into a range of functionalized species.
Rigby, James H.,Kotnis, Atul,Kramer, James
p. 5078 - 5088
(2007/10/02)

SELECTIVE DESULFURIZATION OF 1,3-DITHIANES, -OXATHIOLANES AND -THIAZOLIDINES BY TRIBUTYLTIN HYDRIDE
Selective desulfurization of 2-alkyl-1,3-dithianes, -oxathiolanes, or -thiazolidines 1 with one equivalent of tri-n-butyltin hydride yields acyclic compounds R1R2CHX(CH2)nSSnBu3 (X=S,O,NH; n=2,3), (2) which can be destannylated to the corresponding mercaptans 3.
Schmidt, K.,O'Neal, S.,Chan, T.C.,Alexis, C.P.,Uribe, J.M.,et al.
p. 7301 - 7304
(2007/10/02)

Photochemistry of Stilbenes. 8. Eliminative Photocyclization of o-Methoxystilbenes
The synthetic value of the eliminative photocyclization of o-methoxystilbenes to give phenanthrenes with loss of the element of methanol has been enhanced by the use of tert-butyl alcohol as the solvent and sulfuric acid as a catalyst. 2-Methoxy-5-X-stilbenes and 2-methoxy-3-X-stilbenes undergo this photoreaction to produce the corresponding 2-X-phenanthrenes and 4-X-phenanthrenes, respectively.This regioselective photochemical route to these particular types of substituted phenanthrenes represents an improvement synthetically over the well-known oxidative photocyclization method with meta-substituted stilbenes, from which approximately 1:1 mixtures of 2-substituted and 4-substituted phenanthrenes usually are obtained.An attempt to extend the scope of this eliminative photocyclization method to the synthesis of benzanthracene by the ultraviolet irradiation of 3-methoxy-2-styrylnaphthalene was not successful, but this synthetic objective was achieved in an alternative way by the eliminative photocyclization of 5,6,7,8-tetrahydro-3-methoxy-2-styrylnaphthalene followed by oxidation of the resulting 8,9,10,11-tetrahydrobenzanthracene with DDQ.
Mallory, Frank B.,Rudolph, M. Jonathan,Oh, Soon M.
p. 4619 - 4626
(2007/10/02)

AROMATIC ANNELATION VIA Α-OXOKETENE DITHIOACETALS : SYNTHESIS OF THIORESORCINOL DIMETHYL ETHERS
A novel aromatic annelation leading to fused thioresorcinol dimethyl ethers has been developed by reacting cyclic α-oxoketene dithioacetals with propargylmagnesium bromide followed by treatment of the resulting carbinolacetals with borontrifluoride etherate in methanol.
Gupta, Arun K.,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
p. 1459 - 1462
(2007/10/02)

Inverse Electron Demand Diels-Alder Reactions of 3-Carbomethoxy-2-pyrones. Controlled Introduction of Oxygenated Aromatics: Benzene, Phenol, Catechol, Resorcinol, and Pyrogallol Annulation. Regiospecific Total Synthesis of Sendaverine and a Preparation of 6,7-Benzomorphans
A full investigation of the preparation and Diels-Alder reactions of 3-carbomethoxy-2-pyrones is described.Methods for the preparation of a full range of oxygen-substituted aromatics: benzene, 1-, 2-, or 3-phenol, symmetrical or unsymmetrical o-catechol, resorcinol, and pyrogallol annulation from a common 3-carbomethoxy-2-pyrone intermediate are detailed.A regiospecific total synthesis of sendaverine, a 2-benzyltetrahydroisoquinoline possessing a selectively protected, symmetrical o-catechol, and a preparation of 6,7-benzomorphans are described.
Boger, Dale B.,Mullican, Michael D.
p. 4033 - 4044
(2007/10/02)

INVERSE ELECTRON DEMAND DIELS-ALDER REACTIONS OF 3-CARBOMETHOXY-2-PYRONES. CONTROLLED INTRODUCTION OF OXYGENATED AROMATICS: BENZENE, PHENOL, CATECHOL, RESORCINOL, PYROGALLOL ANNULATION.
Implementation of one of four inverse electron demand Diels-Alder reactions of 3-carbomethoxy-2-pyrones with N-vinyl-2-pyrrolidinone, vinylene carbonate, 1,1-dimethoxy-ethylene or 1,1,2-trimethoxyethylene followed by choice of two standard reaction sequences: (1) removal of the carbomethoxy group (NaOH: copper powder, quinoline , Δ) or (2) its conversion to an acetate allows the preparation of a full range of oxygen substituted aromatics from a single intermediate and represent methods of benzene, 1-, 2- or 3-phenol , symmetrical or unsymmetrical catechol, resorcinol and pyrogallol annulation.
Boger, Dale L.,Mullican, Michael D.
p. 4939 - 4942
(2007/10/02)

1,3-BENZODITHIOLIUM ION MEDIATED ANNULATIONS
A mild and selective method for cyclizations onto aromatic systems using 1,3-benzodithiolium ions is described.
Rigby, James H.,Kotnis, Atul,Kramer, James
p. 2939 - 2940
(2007/10/02)

Neighboring Group Participation in Solvolysis. X. Dissection of Ar1-5 and Ar2-6 Pathways in Trifluoroacetolysis of 4-Arylbutyl 6-Methyl-2-naphthalenesulfonates
Trifluoroacetolysis rates and products were determined for eleven 4-(m- and p-substituted phenyl)butyl 6-methyl-2-naphthalenesulfonates.Most substrates solvolyze predominantly or even exclusively with aryl assisted (kΔ) pathway.Dissection of kΔ into Ar1-5 and Ar2-6 components was performed by means of quantitative 13C NMR study of suitably labeled p-methyl and p-fluoro derivatives; the results were 32.4percent Ar1-5 and 67.6percent Ar2-6 for the former and 43.3percent Ar1-5 and 56.7percent Ar2-6 for the latter.For other substrates the dissection was carried out by postulating two independent linear free energy relationships (LFER) for the two pathways determined by the above four partial rates.Ar2-6 is much prefered over Ar1-5 through the series; for the unsubstituted derivative 90.6percent Ar2-6 vs. 9.4percent Ar1-5 was determined.A completely different approach by means of non-linear regression analysis of kΔ as a sum of two independent LFER gave fairly different and rather unsettled results, limitations of such an approach being suggested.The characteristics of remote aryl participation are discussed based on the above data.
Ando, Takashi,Yamawaki, Junko,Saito, Yoshimasa,Takai, Yoshio,Yamataka, Hiroshi
p. 2348 - 2356
(2007/10/02)

Tri-n-butyltin Hydride: A Selective Reducing Agent for 1,3-Dithiolanes
Tri-n-butyltin hydride has been found to be an effective and selective agent for complete or partial desulfurization of 1,3 dithiolanes 1.The reaction of 1 with 4 equiv of tri-n-butyltin hydride in the presence of 2,2'-azobis(isobutyronitrile) results in complete desulfurization, giving hydrocarbons 2 in good yield, ethane and bis(tri-n-butyltin) sulfide.Two equivalents of hydride specifically cleave the two geminal C-S bonds in 1 to give hydrocarbons 2 and bis(tri-n-butylstannyl) ethanedithiolate.One equivalent of tri-n-butyltin hydride reduces 1 quantitatively to the β-ethyl tri-n-butyltin sulfides 11.
Gutierrez, Carlos G.,Stringham, Rex A.,Nitasaka, Tadashi,Glasscock, Karl G.
p. 3393 - 3395
(2007/10/02)