Chemoselective deprotection of N-Boc group in amino acids and peptides by bismuth(III) trichloride

Navath, Raghavendra S.; Pabbisetty, Kumar

doi:10.1016/j.tetlet.2005.11.003

Cited by 34 publications

(23 citation statements)

References 19 publications

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“…However, the t -BOC can be selectively removed using bismuth (III) trichloride in a mixture of acetonitrile and water, with all other functionalities remaining intact. 26 …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Photodegradable Macromers for Conjugation and Release of Bioactive Molecules

et al. 2013

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Hydrogel scaffolds are used in biomedicine to study cell differentiation and tissue evolution, where it is critical to control the delivery of chemical cues both spatially and temporally. While large molecules can be physically entrapped in a hydrogel, moderate molecular weight therapeutics must be tethered to the hydrogel network through a labile linkage to allow controlled release. We synthesized and characterized a library of polymerizable ortho-nitrobenzyl (o-NB) macromers with different functionalities at the benzylic position (alcohol, amine, BOC-amine, halide, acrylate, carboxylic acid, activated disulfide, N-hydroxysuccinyl ester, biotin). This library of polymerizable macromers containing o-NB groups should allow direct conjugation of nearly any type of therapeutic agent and its subsequent controlled photorelease from a hydrogel network. As proof-of-concept, we incorporated the N-hydroxysuccinyl ester macromer into hydrogels, and then reacted phenylalanine with the NHS ester. Upon exposure to light (λ=365 nm. 10 mW/cm2, 10 min) 81.3% of the phenylalanine was released from the gel. Utilizing the photodegradable macromer incorporating an activated disulfide, we conjugated a cell-adhesive peptide (GCGYGRGDSPG), a protein that exhibits enzymatic activity (bovine serum albumin (BSA)), and a growth factor (transforming growth factor-β1 (TGF-β1)) into hydrogels, controlled their release with light (λ=365 nm. 10 mW/cm2, 0–20 min), and verified the bioactivity of the photoreleased molecules. The photoreleasable peptide allows real-time control over cell adhesion. BSA maintains full enzymatic activity upon sequestration and release from the hydrogel. Photoreleased TGF-β1 is able to induce chondrogenic differentiation of human mesenchymal stem cells comparable to native TGF-β1. Through this approach, we have demonstrated that photodegradable tethers can be used to sequester peptides and proteins into hydrogel depots and release them in an externally controlled, predictable manner without compromising biological function.

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“…However, the t -BOC can be selectively removed using bismuth (III) trichloride in a mixture of acetonitrile and water, with all other functionalities remaining intact. 26 …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Photodegradable Macromers for Conjugation and Release of Bioactive Molecules

et al. 2013

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“…The selective deprotection of ketoximes was achieved in the presence of BiBr 3 (20~40 mol%) and Bi(OTf) 3 ·4H 2 O (5 mol%) in CH 3 CN/ acetone/H 2 O (3:6:1) under reflux conditions [78]. Moreover, BiCl 3 was applied in the chemoselective deprotection of N-Boc group from tryptophan containing peptides, which is an important transformation in the synthesis of peptides and biologically active natural products [79].…”

Section: Bismuth-catalyzed Carbon-oxygen Bond Formation and Cleavage mentioning

confidence: 99%

Recent Advances in Bismuth-Catalyzed Organic Synthesis

Hua

2008

COS

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“…The tert -butyloxycarbonyl protecting group can be removed using trifluoroacetic acid in dichloromethane, but the other esters are simultaneously hydrolyzed so we selectively deprotected the benzylic amine with bismuth trichloride. 27 We then coupled the amine of each o -NB linker to N -hydroxysuccinimide-functionalized fluorophores. We synthesized the fluorescein conjugate of each o -NB group to use for initial kinetic measurements, and we also conjugated each o -NB group to a unique fluorophore (fluorescein, rhodamine and aminomethylcoumarin acetate (AMCA)) as models of different therapeutic agents (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Photoselective Delivery of Model Therapeutics from Hydrogels

Griffin

Kasko

2012

ACS Macro Lett.

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Hydrogels are commonly used in biomedical applications to sequester and release therapeutics. Covalently tethering therapeutic agents to a hydrogel through a degradable linkage allows their controlled release, but temporally separating the release of multiple therapeutics from a single hydrogel remains a major challenge. In this report, we use of a series of photodegradable ortho-nitrobenzyl (o-NB) groups with varying structures to link model therapeutic agents (fluorescein, rhodamine and aminomethylcoumarin acetate) to poly(ethylene glycol) macromers. We polymerized the macromers into hydrogel networks via redox polymerization and quantified the apparent rate constants of degradation (kapp) of each of the photoreleasable compounds. By exploiting differences in reactivity of the different o-NB groups, we are able to create complex, multi-stage release profiles. We demonstrate the ability to switch between concurrent and biased release of model therapeutics simply by switching wavelengths. We also demonstrate a complex four-stage release profile in which the release of three separate model therapeutics is controlled by varying wavelength, intensity and exposure time. This is the first report of photo-selective release of therapeutics from a hydrogel, allowing user-dictated real-time spatial and temporal control over multiple chemical signals in a cell microenvironment in 2D and 3D.

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Chemoselective deprotection of N-Boc group in amino acids and peptides by bismuth(III) trichloride

Cited by 34 publications

References 19 publications

Synthesis of Photodegradable Macromers for Conjugation and Release of Bioactive Molecules

Synthesis of Photodegradable Macromers for Conjugation and Release of Bioactive Molecules

Recent Advances in Bismuth-Catalyzed Organic Synthesis

Photoselective Delivery of Model Therapeutics from Hydrogels

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