Tetrabutylammonium Fluoride (TBAF) as a Mild and Versatile Reagent for Cleaving Boroxazolidones to their Corresponding Free α-Amino Acids

Christian Bernard Matthijs Poulie; Lennart Bunch

doi:10.1002/ejoc.201700063

Tetrabutylammonium Fluoride (TBAF) as a Mild and Versatile Reagent for Cleaving Boroxazolidones to their Corresponding Free α-Amino Acids

Christian Bernard Matthijs Poulie, Lennart Bunch

1 Citation (Scopus)

Abstract

Protection of α-amino acids with 9-borabicyclo[3.3.1]nonane (9-BBN) to give their corresponding boroxazolidones is highly attractive, as it concurrently masks both the amino and the carboxylic acid functionalities. However, the harsh methods required for deprotection of these boroxazolidones have limited their use. Herein, we report that tetrabutylammonium fluoride serves as a mild and versatile reagent that can be used to cleave boroxazolidones to their corresponding free α-amino acids. The reaction conditions were explored, including the use of various nucleophilic fluoride sources, solvents, and reaction temperatures. Nucleophilic fluoride sources comprising an ammonium cation proved superior to other countercations. The scope of the reaction was extended to the cleavage of B,B-diphenyl- and B,B-diethyl boroxazolidone complexes. Furthermore, a wide range of α-amino acid side-chain functionalities were shown to be compatible, including acids, esters, amides, thiols, thioethers, alkynes, phenols, basic heterocycles, and important biorelevant molecules such as glutathione, (S)-adenosyl-l-homocysteine, and l-biocytin.

Original language	Danish
Journal	European Journal of Organic Chemistry
Volume	11
Pages (from-to)	1475-1478
ISSN	1434-193X
DOIs	https://doi.org/10.1002/ejoc.201700063
Publication status	Published - 17 Mar 2017

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10.1002/ejoc.201700063

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@article{43b80c00b0464b8896e5acc26fe79d80,

title = "Tetrabutylammonium Fluoride (TBAF) as a Mild and Versatile Reagent for Cleaving Boroxazolidones to their Corresponding Free α-Amino Acids",

abstract = "Protection of α-amino acids with 9-borabicyclo[3.3.1]nonane (9-BBN) to give their corresponding boroxazolidones is highly attractive, as it concurrently masks both the amino and the carboxylic acid functionalities. However, the harsh methods required for deprotection of these boroxazolidones have limited their use. Herein, we report that tetrabutylammonium fluoride serves as a mild and versatile reagent that can be used to cleave boroxazolidones to their corresponding free α-amino acids. The reaction conditions were explored, including the use of various nucleophilic fluoride sources, solvents, and reaction temperatures. Nucleophilic fluoride sources comprising an ammonium cation proved superior to other countercations. The scope of the reaction was extended to the cleavage of B,B-diphenyl- and B,B-diethyl boroxazolidone complexes. Furthermore, a wide range of α-amino acid side-chain functionalities were shown to be compatible, including acids, esters, amides, thiols, thioethers, alkynes, phenols, basic heterocycles, and important biorelevant molecules such as glutathione, (S)-adenosyl-l-homocysteine, and l-biocytin.",

author = "Poulie, {Christian Bernard Matthijs} and Lennart Bunch",

year = "2017",

month = mar,

day = "17",

doi = "10.1002/ejoc.201700063",

language = "Dansk",

volume = "11",

pages = "1475--1478",

journal = "European Journal of Organic Chemistry",

issn = "1434-193X",

publisher = "Wiley - V C H Verlag GmbH & Co. KGaA",

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TY - JOUR

T1 - Tetrabutylammonium Fluoride (TBAF) as a Mild and Versatile Reagent for Cleaving Boroxazolidones to their Corresponding Free α-Amino Acids

AU - Poulie, Christian Bernard Matthijs

AU - Bunch, Lennart

PY - 2017/3/17

Y1 - 2017/3/17

N2 - Protection of α-amino acids with 9-borabicyclo[3.3.1]nonane (9-BBN) to give their corresponding boroxazolidones is highly attractive, as it concurrently masks both the amino and the carboxylic acid functionalities. However, the harsh methods required for deprotection of these boroxazolidones have limited their use. Herein, we report that tetrabutylammonium fluoride serves as a mild and versatile reagent that can be used to cleave boroxazolidones to their corresponding free α-amino acids. The reaction conditions were explored, including the use of various nucleophilic fluoride sources, solvents, and reaction temperatures. Nucleophilic fluoride sources comprising an ammonium cation proved superior to other countercations. The scope of the reaction was extended to the cleavage of B,B-diphenyl- and B,B-diethyl boroxazolidone complexes. Furthermore, a wide range of α-amino acid side-chain functionalities were shown to be compatible, including acids, esters, amides, thiols, thioethers, alkynes, phenols, basic heterocycles, and important biorelevant molecules such as glutathione, (S)-adenosyl-l-homocysteine, and l-biocytin.

AB - Protection of α-amino acids with 9-borabicyclo[3.3.1]nonane (9-BBN) to give their corresponding boroxazolidones is highly attractive, as it concurrently masks both the amino and the carboxylic acid functionalities. However, the harsh methods required for deprotection of these boroxazolidones have limited their use. Herein, we report that tetrabutylammonium fluoride serves as a mild and versatile reagent that can be used to cleave boroxazolidones to their corresponding free α-amino acids. The reaction conditions were explored, including the use of various nucleophilic fluoride sources, solvents, and reaction temperatures. Nucleophilic fluoride sources comprising an ammonium cation proved superior to other countercations. The scope of the reaction was extended to the cleavage of B,B-diphenyl- and B,B-diethyl boroxazolidone complexes. Furthermore, a wide range of α-amino acid side-chain functionalities were shown to be compatible, including acids, esters, amides, thiols, thioethers, alkynes, phenols, basic heterocycles, and important biorelevant molecules such as glutathione, (S)-adenosyl-l-homocysteine, and l-biocytin.

U2 - 10.1002/ejoc.201700063

DO - 10.1002/ejoc.201700063

M3 - Tidsskriftartikel

SN - 1434-193X

VL - 11

SP - 1475

EP - 1478

JO - European Journal of Organic Chemistry

JF - European Journal of Organic Chemistry

ER -