Mount Allison University - Faculty Publications

Permanent URI for this collectionhttps://hdl.handle.net/1807/78736

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The phosphinoboration of acyl chlorides
(Royal Society of Chemistry, 2020-04-28) Murphy, Maia C.; Trofimova, Alina; LaFortune, James H. W.; Vogels, Christopher M.; Geier, Stephen J.; Binder, Justin F.; Macdonald, Charles L. B.; Stephan, Douglas W.; Westcott, Stephen A.
This investigation examines the reactivity of phosphinoboronate esters Ph2PBpin (pin = 1,2-O2C2Me4) and Ph2PBcat (cat = 1,2-O2C6H4), as well as other phosphinoboron species, with various aryl and aliphatic acyl chlorides. These reactions proceed smoothly to give acyl phosphines of the type RC(O)PR’2 along with loss of a boron-chloride compound. In some cases, a second equivalent of the phosphinoboron species can add to the CvO double bond at elevated temperatures to give the corresponding diphosphines RC(OBR’’2)(PR’2)2. These ambiphilic diphosphines behave like substituted (1,1-bis(diphenylphosphino) methane) derivatives in a reaction of PhC(OBpin)(PPh2)2 2a) with (η5-C9H7)Rh(η2-coe)2 (coe = ciscyclooctene) affording the indenyl rhodium complex (η5-C9H7)Rh(PhC(OBpin)(PPh2)2) (3a) where the phosphines are bound to the metal centre in a κ2-P,P bidentate manner.
Synthesis and antimicrobial properties of cyclic fluorodiamines containing boronate esters
(Wiley, 2017-11) Zhu, Diya; Hunter, Carmanah D.; Baird, Samuel R.; Davis, Bradley R.; Bos, Allyson; Geier, Stephen J.; Vogels, Christopher M.; Decken, Andreas; Gray, Christopher A.; Westcott, Stephen A.
Eight new aminoboron compounds derived from primary diamines and the pinacol-protected product of 3-fluoro-2-formylphenylboronic acid have been prepared and characterized fully. Reactions proceed to give the corresponding cyclic products arising via initial aldimine formation followed by a secondary hydroamination step. One compound contains a pendant amine group which was used to make a novel boron-containing Schiff base ligand along with the corresponding zinc(II) metal complex. All compounds were tested for their initial antimicrobial activities against a number of fungi and bacteria.
Strategic Trimethylsilyldiazomethane Insertion into pinB-SR Followed by Selective Alkylations
(American Chemical Society, 2016-08-05) Civit, Marc G.; Royes, Jordi; Vogels, Christopher M.; Westcott, Stephen A.; Cuenca, Ana B.; Fernández, Elena
The insertion of the diazo derivative Me3SiCHN2 into pinB-SR σ bonds (R = Ph, Tol, Bn) allows a direct synthesis of multisubstituted H-C(SR)(Bpin)(SiMe3) compounds. Consecutive base-assisted transformations of HC(S)(B) (Si) systems lead to deborylative alkylations, Sommelet-Haüser rearrangements, and deprotoalkylations. Intramolecular cyclizations can be selectively performed either via desilylative or deborylative manifolds by fine-tuning the base employed.
The Phosphinoboration of N-Heterocycles
(2017-10-17) Geier, Stephen J; Vogels, Christopher M; Mellonie, Niall R; Daley, Erika N; Decken, Andreas; Doherty, Simon; Westcott, Stephen A
The addition of phosphinoboronate ester Ph2 PBpin (pin=1,2-O2 C2 Me4 ) (1) to a number of different N-heterocycles has been investigated. Reaction of 1 with pyridine resulted in highly selective formation of the corresponding 1,4-addition product, with addition of the electron-deficient Bpin group to the pyridine nitrogen atom and the phosphido group to the para carbon atom. Conversely, reactions of para-substituted pyridine derivatives occurred predominately to afford 1,2-addition products while quinoline reacted to afford the 1,2-adduct which ultimately isomerized to afford the corresponding 1,4-addition product. Preliminary computational studies have been undertaken to explore possible pathways for these transformations including transfer of the PPh2(-) anion from [B(PPh2 )2 pin](-) to the 4-position of a borenium/boronium activated pyridine and concerted pathways for 1,2-addition via intramolecular nucleophilic attack of PPh2 at C2 of a Ph2 PBpin-coordinated pyridine via a four-centered transition state and intramolecular transfer of PPh2 to the 2-position of a boron-activated pyridine in a phosphido-bridged dimer involving a six-centered transition state.
The phosphinoboration of carbodiimides, isocyanates, isothiocyanates and CO2
(Royal Society of Chemistry, 2017-08-22) Geier, Stephen J; LaFortune, James H W; Zhu, Diya; Kosnik, Stephanie C; Macdonald, Charles L B; Stephan, Douglas W; Westcott, Stephen A
The transition metal-free addition of phosphinoboronate ester Ph2PBpin (pin = 1,2-O2C2Me4) to heterocumulenes including carbodiimides, isocyanates, isothiocyanates and carbon dioxide has been investigated. The corresponding 1,2-addition products were readily prepared at room temperature without the need of a catalyst or added base. Addition of methanol to the compounds derived from addition of Ph2PBpin to carbodiimides, isocyanates, and isothiocyanates resulted in traditional hydrophosphination products. The methodology developed in this study provides a simple and elegant route for the generation of a wide range of functionalized phosphines. The phosphinoboronate ester Ph2PBpin also selectively and reversibly adds to CO2 at room temperature in a 1,2-manner.
Rhenium-catalysed hydroboration of aldehydes and aldimines
(Royal Society of Chemistry, 2017-06-28) Arévalo, Rebeca; Vogels, Christopher M; MacNeil, Gregory A; Riera, Lucía; Pérez, Julio; Westcott, Stephen A
The first examples for the rhenium-catalysed hydroboration of aldehydes, ketones and aldimines, including heteroaromatic quinoline, are reported herein. Reactions are remarkably chemoselective and tolerant of several functional groups. A wide array of rhenium complexes were efficient pre-catalysts for these hydroborations, including new low-valent complexes of the formula [Re(N-N)(CO)3(L)]X (N-N = bipy derivative, L = labile ligand/solvent, and X = [BAr(F)4](-) and [B(3,5-di-tBu-cat)2](-)), which have been characterized fully including an X-ray diffraction study for [Re(bipy)(CO)3(quin)][BAr(F)4] (2). A new silver spiroboronate ester Ag[B(3,5-di-tBu-cat)2](NCCH3)3 (3) was prepared and characterized fully, including an X-ray diffraction study, and used to make one of the new rhenium complexes.
Synthesis and Molecular Structure of Ph₃GeBO₂C₂Me₄
(J-STAGE, 2016) BOWES, Eric G.; VOGELS, Christopher M.; DECKEN, Andreas; WESTCOTT, Stephen A.
The germanium-boron compound, Ph3GeBpin (pin = 1,2-O2C2Me4), was isolated and the molecular structure was determined by a single crystal X-ray diffraction study at 188 K. The compound crystallizes in a orthorhombic system, space group Pca2(1) and Z = 8 with cell parameters of a = 16.669(4) Å, b = 9.933(2) Å, c = 26.907(6) Å, V = 4455.0(17) Å3. The R1 [I > 2σ(I)] and wR2 (all data) values are 0.0463 and 0.1196, respectively, for all 9468 independent reflections. The molecular structure analysis reveals the boron atom lies in a roughly trigonal environment that contains one pinacolato group and a single B-Ge bond distance of 2.073(10) Å.
Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse
(American Chemical Society, 2016-08-24) Neeve, Emily C; Geier, Stephen J; Mkhalid, Ibraheem A I; Westcott, Stephen A; Marder, Todd B
Although known for over 90 years, only in the past two decades has the chemistry of diboron(4) compounds been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal-catalyzed and metal-free methodologies for the formation of B-C bonds and other processes.
Synthesis, characterization, and anticancer activities of lipophilic pyridinecarboxaldimine platinum(II) complexes
(Elsevier, 2016-03-29) Miles, Brittany A.; Patterson, Alyssa E.; Vogels, Christopher M.; Decken, Andreas; Waller, Jeffrey C.; Morin, Pier Jr.; Westcott, Stephen A.
Eleven platinum dichloride pyridinecarboxaldimine complexes containing aliphatic groups have been prepared and characterized fully. All platinum complexes were examined for their in vitro cytotoxic properties against two human glioblastoma multiforme cell lines LN18 and LN405.
Synthesis, characterization, and antimicrobial activities of palladium Schiff base complexes derived from aminosalicylic acids
(Springer, 2017-04) Klaus, Jennifer A.; Brooks, Taylor M.; Zhou, Muyang; Veinot, Alex J.; Warman, Alexander M.; Palayew, Adam; Gormley, Patrick T.; Ninh Khuong, B.; Vogels, Christopher M.; Masuda, Jason D.; Baerlocher, Felix J.; Westcott, Stephen A.
Six Schiff base compounds have been prepared from the condensation of o-vanillin, 2,3-dihydroxybenzaldehyde and 2,3,4-trihydroxybenzaldehyde with 4-aminosalicylic acid (4-ASA) and 5-aminosalicylic acid (5-ASA). Addition of these Schiff bases to [Pd(OAc)2] afforded the corresponding bis(salicylaldiminato)palladium(II) complexes in moderate to excellent yields. All new palladium complexes have been characterized fully using standard spectroscopic methods, elemental analyses and a single crystal X-ray diffraction study in the case of 2e, the palladium complex containing Schiff base ligands derived from 5-ASA and 2,3-dihydroxybenzaldehyde. All derivatives of 5-ASA were examined for potential antimicrobial activities against two species of fungi, Aspergillus niger and Saccharomyces cerevisiae, as well as two species of bacteria, Bacillus cereus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative).
Synthesis and characterization of iminophosphineplatinum(II) complexes of the type (κ2-P,N-2-Ph2PC6H4C(H)=NC6H4X)PtCl2 (X = OMe, F)
(Springer, 2017-11) St-Coeur, Patrick-Denis; Adams, Meghan E.; Kenny, Bryanna J.; Stack, Darcie L.; Vogels, Christopher M.; Masuda, Jason D.; Morin, Pier; Westcott, Stephen A.
A series of iminophosphineplatinum(II) complexes have been prepared from pro-ligands derived from aniline derivatives containing electron-donating methoxy groups or electron-withdrawing fluorides and [PtCl2(η2-coe)]2 (coe = cis-cyclooctene). All new pro-ligands and metal complexes have been characterized fully including an X-ray diffraction study for compound 11 (derived from para-methoxyaniline). Additionally, the molecular structure of a di-iminophosphineplatinum dication 11a has been determined. The platinum compounds showed no appreciable cytotoxic properties against two glioma cell lines using the MTT method.
Synthesis, Characterization, and Anticancer Activities of Pyrogallol-Based Arylspiroborates
(Wiley, 2016-11-18) Cormier, Kevin; Curry, R. Daniel; Betsch, Mitchel P.; Goguen, Jeremy A.; Vogels, Christopher M.; Decken, Andreas; Turcotte, Sandra; Westcott, Stephen A.
Arylspiroborate salts derived from pyrogallol, gallic acid, and propyl gallate have been prepared and characterized fully, including an X-ray diffraction study for the tetrabutylammonium gallic acid complex . The tetrabutylammonium salts were examined for their potential anticancer activities against renal cell carcinoma (RCC) cell lines, using NBu4[Bcat2] (cat = catecholato) as a control.

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