Practical and efficient methods for sulfonylation of alcohols using Ts(Ms)Cl/Et3N and catalytic Me3H·HCl as combined base: Promising alternative to traditional pyridine

Yoshida, Yoshitoku; Sakakura, Yoshiko; Aso, Naoya; Okada, Sachiko; Tanabe, Yoo

doi:10.1016/s0040-4020(99)00002-2

Cited by 158 publications

(87 citation statements)

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“…The reaction between ethyl formate (1) and octylmagnesium bromide led to heptadecan-9-ol (2) [27] with a good yield and high purity after distillation under reduced pressure. The tosylate derivative (3) was obtained from compound 2 and p-toluenesulfonyl chloride through a high-performance reaction by Yoshida et al [28] with an excellent yield (89 %). Finally, the alkylation reaction of 2,7-dibromo-9-Hcarbazole [29] with compound 3 was carried out following a procedure described by Marzoni and Garbrecht.…”

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confidence: 99%

A Low‐Bandgap Poly(2,7‐Carbazole) Derivative for Use in High‐Performance Solar Cells

2007

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Harvesting energy directly from sunlight using photovoltaic cells (PCs) is a very important way to address growing global energy needs with a renewable resource while minimizing detrimental effects on the environment. For this purpose, the development of polymeric solar cells has received a great deal of attention from both academic and industrial laboratories. [1][2][3] Indeed, the utilization of semiconducting conjugated polymers as active components in bulk heterojunction photovoltaic devices offers significant potential advantages over existing inorganic materials in terms of ease of processing, formation of large surface areas, and costs. For example, poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-p-phenylenevinylene] (MDMO-PPV), [4] regioregular poly(3-hexylthiophene) (P3HT), [5,6] and other polythiophene derivatives [7] have been extensively studied over the last decade, resulting in PCs with a power conversion efficiency between 3.0 and 5.0 %. However, the performances of these polymers are somehow restricted by their relatively large bandgap and the limited possibilities to modulate their physical properties by synthetic methods. New low-bandgap polymers have been developed over the years to better harvest the solar spectrum, especially in the 1.4-1.9 eV region. Promising copolymers based on fluorene units have been proposed by Andersson/Inganäs [8,9] and Cao, [10] with power conversion efficiencies between 2.0 and 2.8 %. Interestingly, the physical properties of polyfluorene derivatives can be easily modulated through the design of various alternating copolymers.[11] However, relatively low hole mobilities were reported for low-bandgap polyfluorene derivatives. Therefore, besides those recent advances, there is still a need for new polymeric materials to go beyond the 5 % efficiency of actual materials. [3,12,13] Along these lines, poly(N-vinylcarbazole) (PVK) is well known as an excellent photoconductor. [14,15] Furthermore, studies have demonstrated that PVK photoconduction increases when doped with sensitizers like 2,4,7-trinitrofluorenone (TNF) or C 60 . [15,16] In parallel, oligo-and poly(2,7-carbazole) derivatives have been successfully used in polymer lightemitting diodes (PLEDs) [17] and organic field-effect transistors (OFETs), [17,18] demonstrating good p-type transport properties. Recently, Müllen and co-workers [19] have reported solar cells with an efficiency of 0.6 % with poly(N-alkyl-2,7-carbazole), whereas Leclerc and co-workers [20] have shown an efficiency of 0.8 % with poly(2,7-carbazolenevinylene) derivatives. Moreover, in contrast with the fluorene unit the carbazole moiety is fully aromatic, providing a better chemical and environmental stability. Taking all of these results into account, the development of new low-bandgap copolymers based on carbazoles should therefore lead to interesting features for photovoltaic applications. However, poly(N-alkyl-2,7-carbazole)s generally exhibit poor solubilities and low molecular weights. [21] To solve these problems, bulky side chains are us...

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A Low‐Bandgap Poly(2,7‐Carbazole) Derivative for Use in High‐Performance Solar Cells

2007

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“…[8,9] The readily accessible enol triflate derivative (4) [10] of cyclohexane-1,2-dione was found to be a convenient starting material for the synthesis of cyclic allene precursors (Scheme 2). 1,2-Reduction of the enone, [11] derivatization to allylic tosylate 5 under modified conditions, [12] and copper-mediated allylic substitution with We thank NSERC for support of this work, and Dr. Robert McDonald (U. of Alberta X-ray Crystallography Lab) for obtaining the X-ray crystal structure of x.Supporting information for this article is given via a link at the end of the document.Chemistry -A European Journal 10.1002/chem.201602201 COMMUNICATION dimethylphenylsilyllithium provided an efficient and scalable synthesis of allylic silane 3a, [13] equivalent to the previously described precursors. [8,9] Direct copper-mediated conjugate addition using dimethylphenylsilyllithium and capping of the enolate with acetic anhydride [14] afforded allylic silane 3b, a potential precursor to an acetoxy-substituted 1,2-cyclohexadiene.…”

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Efficient Trapping of 1,2‐Cyclohexadienes with 1,3‐Dipoles

Lofstrand

West

2016

Chemistry A European J

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1,2-Cyclohexadienes are transient intermediates that undergo rapid dimerization and intermolecular trapping with activated olefins and heteroatomic nucleophiles. Fluoride-mediated desilylative elimination of readily accessible 6-silylcyclohexene-1-triflates allows the mild, chemoselective, and functional-group tolerant generation of cyclic allene intermediates, which undergo efficient trapping reactions with stable 1,3-dipoles. The reactions proceed with high levels of both regio- and diastereoselectivity. The reaction of cyclic allenes with azides is accompanied by the facile loss of dinitrogen, resulting in the formation of tetrahydroindoles or polycylic aziridines depending on the azide employed.

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“…The two hydroxy groups of aziridine 22 prepared from 20, were protected as TBS ethers to give 31, then the Ns group was introduced to the aziridine to yield 32. 28 When 32 was treated with aqueous ammonia, followed by guanylation with isothiourea 31 gave propargyl guanidine 34a. Treatment of 34a with TBAF led to selective removal of TBS to afford 34b.…”

Section: Bromocyclization Of Propargylguanidinesmentioning

confidence: 99%

A New Synthetic Route to the Skeleton of Saxitoxin, a Naturally Occurring Blocker of Voltage-Gated Sodium Channels

Sawayama¹,

Nishikawa

2012

J. Synth. Org. Chem. Jpn.

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Practical and efficient methods for sulfonylation of alcohols using Ts(Ms)Cl/Et3N and catalytic Me3H·HCl as combined base: Promising alternative to traditional pyridine

Cited by 158 publications

References 11 publications

A Low‐Bandgap Poly(2,7‐Carbazole) Derivative for Use in High‐Performance Solar Cells

A Low‐Bandgap Poly(2,7‐Carbazole) Derivative for Use in High‐Performance Solar Cells

Efficient Trapping of 1,2‐Cyclohexadienes with 1,3‐Dipoles

A New Synthetic Route to the Skeleton of Saxitoxin, a Naturally Occurring Blocker of Voltage-Gated Sodium Channels

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