ivan castillo - Academia.edu (original) (raw)
Papers by ivan castillo
Tetrahedron, 2013
ABSTRACT The synthesis of polydentate amine-S-arythiocarbamates was tested by directed ortho-lith... more ABSTRACT The synthesis of polydentate amine-S-arythiocarbamates was tested by directed ortho-lithiation of 2,4-disubstituted thiophenols, or the corresponding O- and S-arylthiocarbamates by deprotonation or lithium–bromine exchange, followed by addition of the electrophiles N(CH2CH2X)3 (X=Br, I). In the case of the thiophenol, deprotonation resulted in a trithioether-amine upon addition of the electrophile. With the O- and S-thiocarbamates, the reactions resulted in the migration of the thiocarbamoyl group to the ortho-position (Fries rearrangement), or nucleophilic attack of the carbonyl group by butyllithium, respectively. An alternative route employed 2,4-disubstituted phenols to obtain the corresponding salicylaldehydes, and subsequently the O-arylthiocarbamates for Newman–Kwart thermal rearrangement (NKR). Finally, the formyl group on the S-arylthiocarbamates allowed reductive amination to assemble polytopic compounds with amine and S-thiocarbamate groups.
Acta Crystallographica Section C Crystal Structure Communications, 2003
In the title compound, C(17)H(26)N(2)OS(2).CH(2)Cl(2), the C=S distances are 1.650 (4) and 1.679 ... more In the title compound, C(17)H(26)N(2)OS(2).CH(2)Cl(2), the C=S distances are 1.650 (4) and 1.679 (3) A, and the torsion angle between the planes of the thiocarbamate and carbonothioyl fragments is 54.4 (2) degrees. The steric and electronic effects that these substituents exert on one another determine the observed anti configuration with respect to the phenyl C atoms to which they are attached.
ChemInform, 2010
Claisen Rearrangement of Glycine Enolates. Approach to Morphine Synthesis.
Inorganic Chemistry Communications, 2011
a b s t r a c t Reaction of the chiral ligands (1S,4S)-2,5-bis(6-methylpyridyl)-diazabicyclo[2.2.... more a b s t r a c t Reaction of the chiral ligands (1S,4S)-2,5-bis(6-methylpyridyl)-diazabicyclo[2.2.1]heptane (L 1 ), and (1S,4S)-2,5-bis(2-methylbenzimidazolyl)-diazabicyclo[2.2.1]heptane (L 2 ) with copper(II) acetate results in the hydroxo-bridged dicopper complexes [(L 1 )Cu 2 (μ-OH)(H 2 O)(OAc) 2 Cl] (1-Cl·H 2 O), and [(L 2 )Cu(μ-OH)(H 2 O) (MeOH)(OAc) 2 ]OAc (2 . H 2 O,MeOH). Both chiral complexes were characterized spectroscopically, as well as in the solid state by X-ray crystallography.
Tetrahedron Letters, 2010
The Newman-Kwart thermal rearrangement of two 2,4-disubstituted O-arylthiocarbamates, prepared fr... more The Newman-Kwart thermal rearrangement of two 2,4-disubstituted O-arylthiocarbamates, prepared from the corresponding phenols, is reported. Clean conversion to the S-arylthiocarbamates in high yields was observed. The rearrangement appears to be facilitated by the presence of electron-withdrawing substituents in the 2-and 4-positions of the aromatic ring.
![Research paper thumbnail of Synthesis of 1,5-(2,6-dimethylpyridyl)-calix[8]arene: solid-state structure of its dicesium complex](https://attachments.academia-assets.com/46944404/thumbnails/1.jpg)
](Tetrahedron Letters, 2009
![Research paper thumbnail of Calix[8]arene anions: solid state structure of an inclusion compound with a tetrabutylammonium cation](https://attachments.academia-assets.com/46944407/thumbnails/1.jpg)
](Tetrahedron Letters, 2005
Octakis(dimethylsiloxy)-octa-p-tert-butylcalix[8]arene was prepared from the parent p-tert-butylc... more Octakis(dimethylsiloxy)-octa-p-tert-butylcalix[8]arene was prepared from the parent p-tert-butylcalix[8]arene and 1,1,3,3tetramethyldisilazane. Desilylation of the siloxy-calix[8]arene with tetrabutylammonium fluoride hydrate under different conditions afforded di-and tetraanionic derivatives. Determination of the solid state structure of the dianion revealed the formation of an inclusion compound with one tetrabutylammonium cation inside the macrocyclic cavity.
Synlett, 2010
LETTER, Synlett 2010(3): 423-426 DOI: 10.1055/s-0029-1218579. © Georg Thieme Verlag Stuttgart ˙ N... more LETTER, Synlett 2010(3): 423-426 DOI: 10.1055/s-0029-1218579. © Georg Thieme Verlag Stuttgart ˙ New York. Synthesis of N-Boc-Protected Bis(2-benzimidazolylmethyl)amines. Paulina R. Martínez-Alanis a , Manuel López Ortiz b , Ignacio Regla* b , Ivan Castillo* a. ...
Supramolecular Chemistry, 2009
The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalis... more The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalised in the phenolic positions (L 1–L 4) with copper (II) acetate resulted in the formation of discrete complexes or extended coordination polymers. The centrosymmetric ...
Organometallics, 2001
ABSTRACT
Inorganica Chimica Acta - INORG CHIM ACTA, 2010
Deprotonation of the p-tert-butylcalix[4]arene disubstituted at alternate phenolic positions with... more Deprotonation of the p-tert-butylcalix[4]arene disubstituted at alternate phenolic positions with picolyl groups 2 was achieved with alkali metal hydrides LiH, NaH, and KH. The dianionic calixarene derivatives were subjected to complete substitution at the phenolic rim with allyl bromide, providing the tetraalkylated derivatives in cone 3a and partial-cone conformations 3b; both compounds were crystallographically characterized. Compound 2, as well as 3a and 3b were tested as ligands towards CuCl2, affording Cu2+ complexes in the first two cases. Polymeric [2·CuCl2] was obtained from 2 and CuCl2 in MeOH/CH2Cl2 solutions, and consists of chains of the ditopic calixarene acting as an N-donor towards Cu2+ ions outside the macrocyclic cavity. Employment of EtOH/CH2Cl2 mixtures results in the tricopper complex [(2)2Cu3Cl6(EtOH)2]. In contrast, reactions of ligand 3a with CuCl2 afforded monomeric [3a·CuCl2], while no Cu2+ complexes could be obtained when 3b was employed. The presence of intramolecular hydrogen bonds in 2 appears to control the formation of oligomeric or polymeric copper complexes, while the lack of such hydrogen bonds allows the proper alignment of N-donors to coordinate Cu2+ directly above the macrocyclic cavity.Introduction of allyl groups to bispicolyl-calix[4]arene results in the selective preparation of cone and partial-cone tetrasubstituted conformers. The nuclearity of the corresponding CuCl2 complexes is controlled by the crystallization solvent, as well as by the presence or absence of intramolecular hydrogen bonds.
Supramolecular Chemistry, 2009
The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalis... more The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalised in the phenolic positions (L 1–L 4) with copper (II) acetate resulted in the formation of discrete complexes or extended coordination polymers. The centrosymmetric ...
Journal of the Brazilian Chemical Society, 2005
quais mostram diferentes graus de impedimento estérico na posição 2, foram preparados a partir do... more quais mostram diferentes graus de impedimento estérico na posição 2, foram preparados a partir dos correspondentes fenóis. Uma despronotação inicial dos fenóis foi obtida com o uso de NaH em dimetoxietano, seguido de tratamento com cloreto de N,N-dimetiltiocarbomoila, obtendo-se os O-ariltiocarbamatos. A termólise destes compostos resultou num rearranjo, obtendo-se os S-ariltiocarbamatos. Finalmente, a redução dos Sariltiocarbamatos com LiAlH 4 em THF, seguido de acidificação, levou ao isolamento dos tiofenóis. Todos os produtos foram caracterizados por técnicas espectroscópicas, e para alguns tiocarbamatos a estrutura sólida foi determinada por difração de raio X.
Journal of the American Chemical Society, 2001
To investigate the potential role of Sm-Ph species as intermediates in the samarium-catalyzed red... more To investigate the potential role of Sm-Ph species as intermediates in the samarium-catalyzed redistribution of PhSiH 3 to Ph 2 SiH 2 and SiH 4 , the samarium phenyl complex [Cp* 2 SmPh] 2 (1) was prepared by oxidation of Cp* 2 Sm (2) with HgPh 2 . Compound 1 thermally decomposes to yield benzene and the phenylenebridged disamarium complex Cp* 2 Sm(µ-1,4-C 6 H 4 )SmCp* 2 (3). This decomposition reaction appears to proceed through dissociation of 1 into monomeric Cp* 2 SmPh species which then react via unimolecular and bimolecular pathways, involving rate-limiting Cp* metalation and direct C-H activation, respectively. The observed rate law for this process is of the form: rate ) k 1 [1] + k 2 [1] 2 . Complex 1 efficiently transfers its phenyl group to PhSiH 3 , with formation of Ph 2 SiH 2 and [Cp* 2 Sm(µ-H)] 2 (4). Quantitative Si-C bond cleavage of C 6 F 5 SiH 3 is effected by the samarium hydride complex 4, yielding silane and [Cp* 2 Sm(µ-C 6 F 5 )] 2 (5). In contrast, Si-H activation takes place upon reaction of 4 with o-MeOC 6 H 4 SiH 3 , affording the samarium silyl species Cp* 2 SmSiH 2 (o-MeOC 6 H 4 ) (7). Complex 7 rapidly decomposes to [Cp* 2 Sm(µ-o-MeOC 6 H 4 )] 2 (6) and other samarium-containing products. Compounds 5 and 6 were prepared independently by oxidation of 2 with Hg(C 6 F 5 ) 2 and Hg(o-MeOC 6 H 4 ) 2 , respectively. The mechanism of samarium-mediated redistribution at silicon, and chemoselectivity in σ-bond metathesis reactions, are discussed.
Journal of Organometallic Chemistry, 2002
The hafnium imido dichloride (2,6-i-Pr 2 C 6 H 3 )N Hf(THF) 2 Cl 2 (1) reacts with two equivalent... more The hafnium imido dichloride (2,6-i-Pr 2 C 6 H 3 )N Hf(THF) 2 Cl 2 (1) reacts with two equivalents of Ph 3 SiLi(THF) 3 to yield the corresponding disilyl complex (2,6-i-Pr 2 C 6 H 3 )N Hf(THF) 2 (SiPh 3 ) 2 (2) in low yield. Compound 2 was crystallographically characterized. The hafnium monosilyl complex (2,6-i-Pr 2 C 6 H 3 )N Hf(4-t-BuC 5 H 4 N) 2 Cl[Si(SiMe 3 ) 3 ] (4) was synthesized in a similar manner from (2,6-i-Pr 2 C 6 H 3 )N Hf(4-t-BuC 5 H 4 N) 2 Cl 2 (3) and one equivalent of (Me 3 Si) 3 SiK in good yield. The Cp*-containing hafnium imido complex {Cp*HfCl[m-N(2,6-i-Pr 2 C 6 H 3 )]} 2 (5) was prepared by thermolysis of Cp*Hf[Si(SiMe 3 ) 3 ][NH(2,6-i-Pr 2 C 6 H 3 )]Cl via loss of (Me 3 Si) 3 SiH. Complex 5 was crystallographically characterized. Attempts to prepared derivatives of 5 with reactive s-bonds resulted in the formation of Cp*-cyclometallated species.
International Journal of Robust and Nonlinear Control, 2012
This paper proposes a robust fault detection and isolation system for nonlinear processes that ca... more This paper proposes a robust fault detection and isolation system for nonlinear processes that can be formulated as differential algebraic equations. For open-loop stable or closed-loop stabilized systems that operate under strict nonlinear detectability conditions, a methodology to design a nonlinear state estimator based on sliding mode theory was proposed. The extended observer can handle both parameter estimation and parameters with uncertainties. As a result, the state estimator is able to follow the faulty system, detecting faults by examining changes in the controlled outputs with respect to setpoint and then probing variations in the parameters estimated. Once the fault has occurred, the isolation mechanism uses the information provided from the state estimator, generated from recovery actions in the presence of a fault. These differences from normal operation trends can be derived through statistical analysis and then can be used to identify faults. A steam generator system was used to validate this approach, where process faults were considered. The proposed robust fault detection and isolation method shows significant advantages when applied to nonlinear model systems with parameter uncertainties or with complex nonlinearities. The complex nonlinearities can be simplified with algebraic nonlinear functions that have bounded uncertainties in their parameters.
Inorganic Chemistry, 2007
A neutral aminotrithioether interacts with CuI, generating a coordination polymer in the solid st... more A neutral aminotrithioether interacts with CuI, generating a coordination polymer in the solid state. Electrochemical studies indicate that the ligand is prone to oxidation by CuII, which results in a novel C-C bond formation reaction.
Bioorganic & Medicinal Chemistry Letters, 2010
Endocannabinoids (eCBs) are endogenous neuromodulators of synaptic transmission. Their dysfunctio... more Endocannabinoids (eCBs) are endogenous neuromodulators of synaptic transmission. Their dysfunction may cause debilitating disorders of diverse clinical manifestation. For example, drug addiction, lack of sex desire, eating disorders, such as anorexia or bulimia and dyssomnias. eCBs also participate in the regulation of core temperature and pain perception. In this context, it is important to recognize the utility of cannabinoid receptor 1 (CB1R) agonists, natural as Δ9-tetrahydrocannabinol (THC) or synthetic as Nabilone as useful drugs to alleviate this kind of patients’ suffering. Therefore, we have developed a new drug, (R,Z)-18-((1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)-18-oxooctadec-9-en-7-yl phenylacetate (PhAR-DBH-Me), that appears to bind and activate the CB1R. This diazabicyclic amide was synthesized from phenylacetylricinoleic acid and (1S,4S)-2,5-diazabicyclo[2.2.1]heptane. To test its cannabinergic properties we evaluated its effects on core temperature, pain perception, and the sleep-waking cycle of rats. Results indicate that 20 and 40 mg/kg of PhAR-DBH-Me readily reduced core temperature and increased pain perception threshold. In addition, 20 mg/kg increased REM sleep in otherwise normal rats. All these effects were prevented or attenuated by AM251, a CB1R antagonist. Place preference conditioning studies indicated that this molecule does not produce rewarding effects. These results strongly support that PhAR-DBH-Me possesses cannabinoid activity without the reinforcement effects.The synthesis of a new cannabinoid receptor (CB1R) agonist, derived from ricinoleic acid and a chiral diazabicycle is reported.
Tetrahedron, 2013
ABSTRACT The synthesis of polydentate amine-S-arythiocarbamates was tested by directed ortho-lith... more ABSTRACT The synthesis of polydentate amine-S-arythiocarbamates was tested by directed ortho-lithiation of 2,4-disubstituted thiophenols, or the corresponding O- and S-arylthiocarbamates by deprotonation or lithium–bromine exchange, followed by addition of the electrophiles N(CH2CH2X)3 (X=Br, I). In the case of the thiophenol, deprotonation resulted in a trithioether-amine upon addition of the electrophile. With the O- and S-thiocarbamates, the reactions resulted in the migration of the thiocarbamoyl group to the ortho-position (Fries rearrangement), or nucleophilic attack of the carbonyl group by butyllithium, respectively. An alternative route employed 2,4-disubstituted phenols to obtain the corresponding salicylaldehydes, and subsequently the O-arylthiocarbamates for Newman–Kwart thermal rearrangement (NKR). Finally, the formyl group on the S-arylthiocarbamates allowed reductive amination to assemble polytopic compounds with amine and S-thiocarbamate groups.
Acta Crystallographica Section C Crystal Structure Communications, 2003
In the title compound, C(17)H(26)N(2)OS(2).CH(2)Cl(2), the C=S distances are 1.650 (4) and 1.679 ... more In the title compound, C(17)H(26)N(2)OS(2).CH(2)Cl(2), the C=S distances are 1.650 (4) and 1.679 (3) A, and the torsion angle between the planes of the thiocarbamate and carbonothioyl fragments is 54.4 (2) degrees. The steric and electronic effects that these substituents exert on one another determine the observed anti configuration with respect to the phenyl C atoms to which they are attached.
ChemInform, 2010
Claisen Rearrangement of Glycine Enolates. Approach to Morphine Synthesis.
Inorganic Chemistry Communications, 2011
a b s t r a c t Reaction of the chiral ligands (1S,4S)-2,5-bis(6-methylpyridyl)-diazabicyclo[2.2.... more a b s t r a c t Reaction of the chiral ligands (1S,4S)-2,5-bis(6-methylpyridyl)-diazabicyclo[2.2.1]heptane (L 1 ), and (1S,4S)-2,5-bis(2-methylbenzimidazolyl)-diazabicyclo[2.2.1]heptane (L 2 ) with copper(II) acetate results in the hydroxo-bridged dicopper complexes [(L 1 )Cu 2 (μ-OH)(H 2 O)(OAc) 2 Cl] (1-Cl·H 2 O), and [(L 2 )Cu(μ-OH)(H 2 O) (MeOH)(OAc) 2 ]OAc (2 . H 2 O,MeOH). Both chiral complexes were characterized spectroscopically, as well as in the solid state by X-ray crystallography.
Tetrahedron Letters, 2010
The Newman-Kwart thermal rearrangement of two 2,4-disubstituted O-arylthiocarbamates, prepared fr... more The Newman-Kwart thermal rearrangement of two 2,4-disubstituted O-arylthiocarbamates, prepared from the corresponding phenols, is reported. Clean conversion to the S-arylthiocarbamates in high yields was observed. The rearrangement appears to be facilitated by the presence of electron-withdrawing substituents in the 2-and 4-positions of the aromatic ring.
Tetrahedron Letters, 2009
Tetrahedron Letters, 2005
Octakis(dimethylsiloxy)-octa-p-tert-butylcalix[8]arene was prepared from the parent p-tert-butylc... more Octakis(dimethylsiloxy)-octa-p-tert-butylcalix[8]arene was prepared from the parent p-tert-butylcalix[8]arene and 1,1,3,3tetramethyldisilazane. Desilylation of the siloxy-calix[8]arene with tetrabutylammonium fluoride hydrate under different conditions afforded di-and tetraanionic derivatives. Determination of the solid state structure of the dianion revealed the formation of an inclusion compound with one tetrabutylammonium cation inside the macrocyclic cavity.
Synlett, 2010
LETTER, Synlett 2010(3): 423-426 DOI: 10.1055/s-0029-1218579. © Georg Thieme Verlag Stuttgart ˙ N... more LETTER, Synlett 2010(3): 423-426 DOI: 10.1055/s-0029-1218579. © Georg Thieme Verlag Stuttgart ˙ New York. Synthesis of N-Boc-Protected Bis(2-benzimidazolylmethyl)amines. Paulina R. Martínez-Alanis a , Manuel López Ortiz b , Ignacio Regla* b , Ivan Castillo* a. ...
Supramolecular Chemistry, 2009
The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalis... more The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalised in the phenolic positions (L 1–L 4) with copper (II) acetate resulted in the formation of discrete complexes or extended coordination polymers. The centrosymmetric ...
Organometallics, 2001
ABSTRACT
Inorganica Chimica Acta - INORG CHIM ACTA, 2010
Deprotonation of the p-tert-butylcalix[4]arene disubstituted at alternate phenolic positions with... more Deprotonation of the p-tert-butylcalix[4]arene disubstituted at alternate phenolic positions with picolyl groups 2 was achieved with alkali metal hydrides LiH, NaH, and KH. The dianionic calixarene derivatives were subjected to complete substitution at the phenolic rim with allyl bromide, providing the tetraalkylated derivatives in cone 3a and partial-cone conformations 3b; both compounds were crystallographically characterized. Compound 2, as well as 3a and 3b were tested as ligands towards CuCl2, affording Cu2+ complexes in the first two cases. Polymeric [2·CuCl2] was obtained from 2 and CuCl2 in MeOH/CH2Cl2 solutions, and consists of chains of the ditopic calixarene acting as an N-donor towards Cu2+ ions outside the macrocyclic cavity. Employment of EtOH/CH2Cl2 mixtures results in the tricopper complex [(2)2Cu3Cl6(EtOH)2]. In contrast, reactions of ligand 3a with CuCl2 afforded monomeric [3a·CuCl2], while no Cu2+ complexes could be obtained when 3b was employed. The presence of intramolecular hydrogen bonds in 2 appears to control the formation of oligomeric or polymeric copper complexes, while the lack of such hydrogen bonds allows the proper alignment of N-donors to coordinate Cu2+ directly above the macrocyclic cavity.Introduction of allyl groups to bispicolyl-calix[4]arene results in the selective preparation of cone and partial-cone tetrasubstituted conformers. The nuclearity of the corresponding CuCl2 complexes is controlled by the crystallization solvent, as well as by the presence or absence of intramolecular hydrogen bonds.
Supramolecular Chemistry, 2009
The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalis... more The reactions of mono-, bis-and tetrapicolyl-p-tert-butylcalix [4] arene derivatives functionalised in the phenolic positions (L 1–L 4) with copper (II) acetate resulted in the formation of discrete complexes or extended coordination polymers. The centrosymmetric ...
Journal of the Brazilian Chemical Society, 2005
quais mostram diferentes graus de impedimento estérico na posição 2, foram preparados a partir do... more quais mostram diferentes graus de impedimento estérico na posição 2, foram preparados a partir dos correspondentes fenóis. Uma despronotação inicial dos fenóis foi obtida com o uso de NaH em dimetoxietano, seguido de tratamento com cloreto de N,N-dimetiltiocarbomoila, obtendo-se os O-ariltiocarbamatos. A termólise destes compostos resultou num rearranjo, obtendo-se os S-ariltiocarbamatos. Finalmente, a redução dos Sariltiocarbamatos com LiAlH 4 em THF, seguido de acidificação, levou ao isolamento dos tiofenóis. Todos os produtos foram caracterizados por técnicas espectroscópicas, e para alguns tiocarbamatos a estrutura sólida foi determinada por difração de raio X.
Journal of the American Chemical Society, 2001
To investigate the potential role of Sm-Ph species as intermediates in the samarium-catalyzed red... more To investigate the potential role of Sm-Ph species as intermediates in the samarium-catalyzed redistribution of PhSiH 3 to Ph 2 SiH 2 and SiH 4 , the samarium phenyl complex [Cp* 2 SmPh] 2 (1) was prepared by oxidation of Cp* 2 Sm (2) with HgPh 2 . Compound 1 thermally decomposes to yield benzene and the phenylenebridged disamarium complex Cp* 2 Sm(µ-1,4-C 6 H 4 )SmCp* 2 (3). This decomposition reaction appears to proceed through dissociation of 1 into monomeric Cp* 2 SmPh species which then react via unimolecular and bimolecular pathways, involving rate-limiting Cp* metalation and direct C-H activation, respectively. The observed rate law for this process is of the form: rate ) k 1 [1] + k 2 [1] 2 . Complex 1 efficiently transfers its phenyl group to PhSiH 3 , with formation of Ph 2 SiH 2 and [Cp* 2 Sm(µ-H)] 2 (4). Quantitative Si-C bond cleavage of C 6 F 5 SiH 3 is effected by the samarium hydride complex 4, yielding silane and [Cp* 2 Sm(µ-C 6 F 5 )] 2 (5). In contrast, Si-H activation takes place upon reaction of 4 with o-MeOC 6 H 4 SiH 3 , affording the samarium silyl species Cp* 2 SmSiH 2 (o-MeOC 6 H 4 ) (7). Complex 7 rapidly decomposes to [Cp* 2 Sm(µ-o-MeOC 6 H 4 )] 2 (6) and other samarium-containing products. Compounds 5 and 6 were prepared independently by oxidation of 2 with Hg(C 6 F 5 ) 2 and Hg(o-MeOC 6 H 4 ) 2 , respectively. The mechanism of samarium-mediated redistribution at silicon, and chemoselectivity in σ-bond metathesis reactions, are discussed.
Journal of Organometallic Chemistry, 2002
The hafnium imido dichloride (2,6-i-Pr 2 C 6 H 3 )N Hf(THF) 2 Cl 2 (1) reacts with two equivalent... more The hafnium imido dichloride (2,6-i-Pr 2 C 6 H 3 )N Hf(THF) 2 Cl 2 (1) reacts with two equivalents of Ph 3 SiLi(THF) 3 to yield the corresponding disilyl complex (2,6-i-Pr 2 C 6 H 3 )N Hf(THF) 2 (SiPh 3 ) 2 (2) in low yield. Compound 2 was crystallographically characterized. The hafnium monosilyl complex (2,6-i-Pr 2 C 6 H 3 )N Hf(4-t-BuC 5 H 4 N) 2 Cl[Si(SiMe 3 ) 3 ] (4) was synthesized in a similar manner from (2,6-i-Pr 2 C 6 H 3 )N Hf(4-t-BuC 5 H 4 N) 2 Cl 2 (3) and one equivalent of (Me 3 Si) 3 SiK in good yield. The Cp*-containing hafnium imido complex {Cp*HfCl[m-N(2,6-i-Pr 2 C 6 H 3 )]} 2 (5) was prepared by thermolysis of Cp*Hf[Si(SiMe 3 ) 3 ][NH(2,6-i-Pr 2 C 6 H 3 )]Cl via loss of (Me 3 Si) 3 SiH. Complex 5 was crystallographically characterized. Attempts to prepared derivatives of 5 with reactive s-bonds resulted in the formation of Cp*-cyclometallated species.
International Journal of Robust and Nonlinear Control, 2012
This paper proposes a robust fault detection and isolation system for nonlinear processes that ca... more This paper proposes a robust fault detection and isolation system for nonlinear processes that can be formulated as differential algebraic equations. For open-loop stable or closed-loop stabilized systems that operate under strict nonlinear detectability conditions, a methodology to design a nonlinear state estimator based on sliding mode theory was proposed. The extended observer can handle both parameter estimation and parameters with uncertainties. As a result, the state estimator is able to follow the faulty system, detecting faults by examining changes in the controlled outputs with respect to setpoint and then probing variations in the parameters estimated. Once the fault has occurred, the isolation mechanism uses the information provided from the state estimator, generated from recovery actions in the presence of a fault. These differences from normal operation trends can be derived through statistical analysis and then can be used to identify faults. A steam generator system was used to validate this approach, where process faults were considered. The proposed robust fault detection and isolation method shows significant advantages when applied to nonlinear model systems with parameter uncertainties or with complex nonlinearities. The complex nonlinearities can be simplified with algebraic nonlinear functions that have bounded uncertainties in their parameters.
Inorganic Chemistry, 2007
A neutral aminotrithioether interacts with CuI, generating a coordination polymer in the solid st... more A neutral aminotrithioether interacts with CuI, generating a coordination polymer in the solid state. Electrochemical studies indicate that the ligand is prone to oxidation by CuII, which results in a novel C-C bond formation reaction.
Bioorganic & Medicinal Chemistry Letters, 2010
Endocannabinoids (eCBs) are endogenous neuromodulators of synaptic transmission. Their dysfunctio... more Endocannabinoids (eCBs) are endogenous neuromodulators of synaptic transmission. Their dysfunction may cause debilitating disorders of diverse clinical manifestation. For example, drug addiction, lack of sex desire, eating disorders, such as anorexia or bulimia and dyssomnias. eCBs also participate in the regulation of core temperature and pain perception. In this context, it is important to recognize the utility of cannabinoid receptor 1 (CB1R) agonists, natural as Δ9-tetrahydrocannabinol (THC) or synthetic as Nabilone as useful drugs to alleviate this kind of patients’ suffering. Therefore, we have developed a new drug, (R,Z)-18-((1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)-18-oxooctadec-9-en-7-yl phenylacetate (PhAR-DBH-Me), that appears to bind and activate the CB1R. This diazabicyclic amide was synthesized from phenylacetylricinoleic acid and (1S,4S)-2,5-diazabicyclo[2.2.1]heptane. To test its cannabinergic properties we evaluated its effects on core temperature, pain perception, and the sleep-waking cycle of rats. Results indicate that 20 and 40 mg/kg of PhAR-DBH-Me readily reduced core temperature and increased pain perception threshold. In addition, 20 mg/kg increased REM sleep in otherwise normal rats. All these effects were prevented or attenuated by AM251, a CB1R antagonist. Place preference conditioning studies indicated that this molecule does not produce rewarding effects. These results strongly support that PhAR-DBH-Me possesses cannabinoid activity without the reinforcement effects.The synthesis of a new cannabinoid receptor (CB1R) agonist, derived from ricinoleic acid and a chiral diazabicycle is reported.