Simple, High-Yield Synthesis of Polyhedral Carborane Amino Acids

Kahl, Stephen B.; Kasar, R. A.

doi:10.1021/ja9534260

Cited by 67 publications

(46 citation statements)

References 15 publications

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“…C-Hydroxycarbonyl-o-carborane 1e, which is commercially available, was transformed into amine 1f by Curtius rearrangement. 36) The m-and pcarborane derivatives 2a-d, [32][33][34][35] 2f, [36][37][38][39] 3a-d [32][33][34][35] and 3f [36][37][38][39] were synthesized in the same manner as the o-carborane derivatives.…”

mentioning

confidence: 99%

Complexation of .ALPHA.-Cyclodextrin with Carborane Derivatives in Aqueous Solution

Ohta

Konno

Endo

2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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NotesIcosahedral carboranes (dicarba-closo-dodecaboranes) have unique structural and chemical properties, such as high boron content, spherical structure, three isomers (ortho, meta and para), a highly hydrophobic surface, and unexpected thermal and chemical stability (Fig. 1).1,2) Biomedical applications of the carboranes, e.g., in boron neutron capture therapy (BNCT), are of great interest. [3][4][5] We have reported applications of carboranes in medicinal drug design as a hydrophobic component of biologically active molecules, 6) targeting nuclear receptors, such as estrogen receptor (ER), 7,8) androgen receptor (AR), 9,10) retinoic acid receptor (RAR) 11,12) and retinoid X receptor (RXR).13) It was suggested that the carborane cage works as a hydrophobic group for binding to the hydrophobic cavity of the ligand-binding domain (LBD) on the nuclear receptors, and that hydrophobic van der Waals contacts along the spherical carborane cage produce a stronger interaction than that in the case of the native ligand. In the development of carborane-containing estrogen ligands, we have investigated the hydrophobicity of carboranes by measuring the partition coefficients, log P values, and the hydrophobicity parameter p. 14,15) Cyclodextrins (CDs) are widely used as host molecules in a number of areas of chemistry where molecular recognition is required, such as material sciences, supramolecular chemistry, molecular-sensing, and artificial enzymes (Fig. 1). Moreover, CDs are of great utility in the field of medicinal chemistry as solubilizing agents for lipophilic drugs, [16][17][18] as photostabilizers of light-sensitive drugs, [19][20][21] and as sustained-release [16][17][18] and drug delivery systems [22][23][24] for various drugs.Complexes of a-, b-, and g-CD with unsubstituted ocarborane (1a) were isolated, and the stoichiometries of the complexes were determined by elemental analysis and from the ratios of the 1 H-NMR peaks.25) However, the stoichiometric ratio, association constant and complex formation in solution have not been well characterized. Recently, Threadgill and co-workers have reported the formation of a remarkably robust 2 : 1 complex of b-CD with 1-phenyl-o-carborane. 26)An excellent fit of the carborane cage with b-CD was confirmed by a molecular modelling study. This work dealt only with the o-carborane isomer. The attractive properties of mand p-carboranes 27) mean that complexation of these molecules with CDs is also of interest. It is noteworthy that b-CDbonded chiral stationary phases have been used for enantiomeric resolution in the ten-vertex carborane series, 28,29) implying a strong interaction of ten-vertex carborane with b-CD.However, the host-guest complexations of carboranes with CDs are not well understood. Therefore, we have focused on the interaction between the spherical, hydrophobic surface of carboranes and the hydrophobic pocket of CDs. Recently, we reported the complexation of carborane derivatives with b-CD, including association constant values and stoichiometry in aqueous ...

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confidence: 99%

Complexation of .ALPHA.-Cyclodextrin with Carborane Derivatives in Aqueous Solution

Ohta

Konno

Endo

2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Removal of the solvent under reduced pressure yielded 1.42 g of the colorless crude product 6a. 1 13 C NMR: δ 106.6, 66.5, 63.9, 63.7, 37.6, 26.6. MS: 144 (M + ) .…”

Section: Synthesis Of 3-hydroxymethylcyclobutanone Ethylene Ketal (6a)mentioning

confidence: 99%

Synthesis of a novel boronated 1‐aminocyclobutanecarboxylic acid as a potential boron neutron capture therapy agent

Kabalka¹,

Yao²

2003

Applied Organom Chemis

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A boronated aminocyclobutanecarboxylic acid was synthesized for potential use in neutron capture therapy. The synthesis involves the preparation of hydroxymethylcyclobutanone ketal, which is then converted to an amino acid using Bucherer-Strecker methodology. The molecule is modeled after the unnatural amino acid, 1-aminocyclobutanecarboxylic acid, which has demonstrated high uptake in brain tumors.

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“…It also demonstrates our recently developed strategy for efficient differentiation of the two carbon atoms in 6 using a Ph 3 Si substituent, which induces crystallinity and UV activity facilitating isolation, purification and storage of the products and intermediates 82 . Other methods for heterodisubstitution in 6 (refs 87,88 ), 10 (ref. 12 ), and 4 (refs 89,90 ) are less general.…”

Section: Carbon Substitutionmentioning

confidence: 99%

“…There are relatively few examples of C-N bond formation. Direct amination of dilithio-para-carborane with MeONHLi has been reported to give a mixture of the 1-amino-and 1,12-diamino-paracarboranes 87 . Attempts to extend this procedure to [12-(n-C 7 H 15 )-1-Li-CB 11 H 10 ] resulted in only traces of the desired 1-amino product 94 .…”

Section: Carbon Substitutionmentioning

confidence: 99%

Four Decades of Organic Chemistry of closo-Boranes: A Synthetic Toolbox for Constructing Liquid Crystal Materials. A Review

Kaszyński

1999

Collect. Czech. Chem. Commun.

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Introduction and transformations of organic functional groups to ten- and twelve-vertex closo-boranes and heteroboranes is reviewed in the context of preparation of liquid crystalline compounds. The review, containing 198 references, is designed as a synthetic manual for materials chemists and focuses on methods for engineering molecules with elongated shapes and variable dipole moments. Several underdeveloped aspects of closo-borane chemistry are identified.

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Simple, High-Yield Synthesis of Polyhedral Carborane Amino Acids

Cited by 67 publications

References 15 publications

Complexation of .ALPHA.-Cyclodextrin with Carborane Derivatives in Aqueous Solution

Complexation of .ALPHA.-Cyclodextrin with Carborane Derivatives in Aqueous Solution

Synthesis of a novel boronated 1‐aminocyclobutanecarboxylic acid as a potential boron neutron capture therapy agent

Four Decades of Organic Chemistry of closo-Boranes: A Synthetic Toolbox for Constructing Liquid Crystal Materials. A Review

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