A convenient one-step synthesis of hydrocarbons from alcohols through use of the organosilane-boron trifluoride reducing system

Adlington, Merwyn G.; Orfanopoulos, Michael; Fry, James L.

doi:10.1016/s0040-4039(01)85498-8

Cited by 98 publications

(59 citation statements)

References 8 publications

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“…Fluorous Technologies Inc. (Pittsburgh, PA) synthesized the nine compounds in Fig. 6 with an ortholithiation-deoxygenation procedure based on previous publications (McOmie and West, 1973;Adlington et al, 1976;Green et al, 2000) (Scheme 1). Structures were verified by nuclear magnetic resonance.…”

Section: Methodsmentioning

confidence: 99%

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Salvador-Recatalà¹,

Kim²,

Zaks-Makhina³

et al. 2006

J Pharmacol Exp Ther

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High-throughput screening led to the identification of a 3-norbornyl derivative of catechol called 48F10 (3-bicyclo[2.2.1]hept-2-yl-benzene-1,2-diol) as a Kv2.1 K ϩ channel inhibitor. By virtue of the involvement of Kv2.1 channels in programmed cell death, 48F10 prevents apoptosis in cortical neurons and enterocytes. This uncharged compound acts with an apparent affinity of 1 M at the tetraethylammonium (TEA) site at the external mouth of the Kv2.1 channel but is ineffective on Kv1.5. Here we investigated the basis of this selectivity with structure-activity studies. We find that catechol (1,2-benzenediol), unlike 48F10, inhibits Kv2.1 currents with a Hill coefficient of 2 and slows channel activation. Furthermore, this inhibition, which requires millimolar concentrations, is unaffected by external TEA or by mutation of the external tyrosine implicated in channel block by TEA and 48F10. In addition, catechol does not distinguish between Kv2.1 and Kv1.5. Thus, catechol acts at conserved sites that are distinct from 48F10. We also tested 11 catechol derivatives based on hydrocarbon adducts including norbornyl substructures, a 48F10 isomer, and a 48F10 diastereomer. These compounds are more potent than catechol, but none replicated the marked selectivity of 48F10 for Kv2.1 over Kv1.5. We conclude that the targeting of 48F10 to the TEA site at the external mouth of the Kv2.1 pore and away from other sites involved in nonselective Kv channel block by catechol requires the norbornyl group in a unique position and orientation on the catechol ring.

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Section: Methodsmentioning

confidence: 99%

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Salvador-Recatalà¹,

Kim²,

Zaks-Makhina³

et al. 2006

J Pharmacol Exp Ther

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“…One can readily envisage cleavage of the long C3 À C4 bond (1.605 ) in 6 to regenerate the tetramethylene ethane diradical having a phenyl and a biphenylene group, which can exist in three isomeric forms: endo,endo (12), endo,exo (13) and exo,exo (14). Now, following the allene dimerization mechanism proposed by Christl, [13] conrotatory ring closure of endo,endo form 13 leads to red trans dimer 7, while, at successively higher temperatures endo,exo and exo,exo isomers 13 and 14 lead to the orange cis and orange trans products 8 and 9, respectively.…”

Section: Mechanisticmentioning

confidence: 99%

“…[14] The mechanism presumably involves coordination of the hydroxyl group to boron, transfer of fluorine from boron to silicon and delivery of a hydride from silicon to carbon to furnish the desired alkyne 1, possibly via single cyclic transition state. In our hands, the reaction works reasonably satisfactorily (50-60 % yield of isolated product) and the alkyne has been characterized by X-ray crystallography.…”

Section: Mechanisticmentioning

confidence: 99%

Sequential Formation of Yellow, Red, and Orange 1‐Phenyl‐3,3‐Biphenylene‐Allene Dimers Prior to Blue Tetracene Formation: Helicity Reversal in trans‐3,4‐Diphenyl‐1,2‐bis(fluorenylidene)cyclobutane

Banide

Ortin

Seward

et al. 2006

Chemistry A European J

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1-Phenyl-3,3-biphenyleneallene (2), the base-catalyzed rearrangement product of 9-phenylethynylfluorene (1) yields a yellow, head-to-tail dimer 6 that, upon gentle warming, is converted to the red tail-to-tail isomer trans-3,4-diphenyl-1,2-bis(fluorenylidene)cyclobutane (7), in which the two fluorenylidene moieties severely overlap. The helical sense of the fluorenylidene moieties in 7 matches that of the phenyl substituents, and the interplanar angle between the fluorenylidene moieties is 41 degrees . At 80 degrees C, 6 isomerizes to orange cis-3,4-diphenyl-1,2-bis(fluorenylidene)cyclobutane (8), which at 110 degrees C is converted to orange trans diastereomer 9, whereby the helicity of the overlapping fluorenylidene moieties is reversed from that in 7 such that they are aligned with the ring hydrogen atoms, and the interplanar angle between the fluorenylidene moieties is now 60 degrees . At 180 degrees C, 6 rearranges to dispirodihydrotetracene 3 and blue, electroluminescent diindenotetracene 4, which is readily oxidized to peroxide 5. In the solid state, both 3 and 4 adopt structures with Ci symmetry (only an inversion center) such that the central polycyclic framework is nonplanar. Deprotonation of yellow head-to-tail allene dimer 6 with tBuOK in DMSO and reprotonation with HOAc yields the [1,3]-hydrogen migration product 10, in which the proton originally on the cyclobutane ring is now sited at C9 on the exocyclic fluorenyl substituent. Analogously, deprotonation and reprotonation of orange dimer 9 furnishes [1,3]-hydrogen migration product 11. Side product 17, formed during the synthesis of 1 from 9-phenylethynylfluoren-9-ol, BF3 and Et3SiH, was shown to be a silyl-indene spiro-linked to C9 of fluorene. All products were characterized by NMR spectroscopy and X-ray crystallography, and the mechanisms of these interconversions are discussed.

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“…[1][2][3] As depicted in Scheme 1, treatment of fluorenone with an alkynyllithium yields the corresponding 9-alkynylfluoren-9-ol, 1. Conversion to the required 3,3-(biphenyl-2,2Ј-diyl)-1-arylallene 3 can be accomplished either by reaction with BF 3 /Et 3 SiH (to form an alkyne 2, which readily rearranges under basic conditions) [4][5][6] or by formation of the bromoallene 4, [7] followed by lithiation and hydrolysis. [8] Subsequent thermolysis of the allenes yields tetracenes 5.…”

Section: Introductionmentioning

confidence: 99%

A Synthetic and X‐ray Crystallographic Study of Zinc and Platinum Complexes of 4,5‐Diazafluoren‐9‐one (Dafone) and Dicobalt Hexacarbonyl Derivatives of 9‐Phenylethynyl‐4,5‐Diazafluoren‐9‐ol: Chelation versus Monocoordination

et al. 2009

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Reaction of 4,5‐diazafluoren‐9‐one (dafone, 6) and zinc dichloride yields [(dafone)ZnCl2(H2O)] (11) in which the ZnCl2 moiety is coordinated to a single nitrogen atom and also to a molecule of water. Hydrogen bonding, not only to the uncomplexed nitrogen atom of dafone but also to the ketonic oxygen atom of a neighbouring molecule, leads to a zigzag chain structure. In contrast, reaction with anhydrous zinc iodide forms cis‐(dafone)2ZnI2 (12) in which the metal–nitrogen distances – 2.170(5) and 2.456(5) Å – are significantly different. Dafone, in the presence of dimethyl sulfoxide, reacts with K2PtCl4 to produce square‐planar (dafone)PtCl2(dmso) (13), whereas with K2PtBr6 the octahedral complex (dafone)PtBr4 (14) is formed in which the ligand chelates in a symmetrical fashion. Treatment of dafone with phenylethynyllithium furnishes 9‐phenylethynyl‐4,5‐diazafluoren‐9‐ol (7), which forms a square‐planar nitrogen‐bonded PtCl2 complex, 15. Reaction of 7 with Co2(CO)8 yields the (μ‐alkyne)hexacarbonyldicobalt cluster 17, which undergoes protonation at the nitrogen atom to form 20 rather than at the alcohol to form a cobalt‐complexed propargyl cation. Alkynol 7 also reacts with HBr by addition across the triple bond to form Z‐9‐[(2‐bromo‐2‐phenyl)ethenyl]‐4,5‐diazafluoren‐9‐ol (10). X‐ray crystal structures are reported for 6, 7, 10–15, 17 and 20, and their differing hydrogen‐bonding motifs are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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A convenient one-step synthesis of hydrocarbons from alcohols through use of the organosilane-boron trifluoride reducing system

Cited by 98 publications

References 8 publications

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Sequential Formation of Yellow, Red, and Orange 1‐Phenyl‐3,3‐Biphenylene‐Allene Dimers Prior to Blue Tetracene Formation: Helicity Reversal in trans‐3,4‐Diphenyl‐1,2‐bis(fluorenylidene)cyclobutane

A Synthetic and X‐ray Crystallographic Study of Zinc and Platinum Complexes of 4,5‐Diazafluoren‐9‐one (Dafone) and Dicobalt Hexacarbonyl Derivatives of 9‐Phenylethynyl‐4,5‐Diazafluoren‐9‐ol: Chelation versus Monocoordination

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A convenient one-step synthesis of hydrocarbons from alcohols through use of the organosilane-boron trifluoride reducing system

Cited by 98 publications

References 8 publications

Voltage-Gated K+ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Voltage-Gated K+ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Sequential Formation of Yellow, Red, and Orange 1‐Phenyl‐3,3‐Biphenylene‐Allene Dimers Prior to Blue Tetracene Formation: Helicity Reversal in trans‐3,4‐Diphenyl‐1,2‐bis(fluorenylidene)cyclobutane

A Synthetic and X‐ray Crystallographic Study of Zinc and Platinum Complexes of 4,5‐Diazafluoren‐9‐one (Dafone) and Dicobalt Hexacarbonyl Derivatives of 9‐Phenylethynyl‐4,5‐Diazafluoren‐9‐ol: Chelation versus Monocoordination

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Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores