Chemoselective N-Boc Protection Research Articles

Malic Acid as a Green Catalyst for the N-Boc Protection under Solvent-free Condition

Abstract: A protocol for the Chemoselective N-Boc protection of various types of amines has been developed. This includes heteroaryl, aliphatic, and alicyclic amines. The process makes use of malic acid as a catalyst and operates efficiently at ambient temperature without the need for solvents. This technique has been proven to effectively protect a wide range of functionalized amines containing both electron-donating and electron-withdrawing substituents. The benefits of this method include its fast reaction rate, high selectivity, excellent yield, catalyst recyclability, and environmentally friendly conditions.

Sulfated tungstate: A highly efficient, recyclable and ecofriendly catalyst for chemoselective N-tert butyloxycarbonylation of amines under the solvent-free conditions

Sulfated tungstate catalyzed an efficient and ecofriendly protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at room temperature. The variety of functionalized aliphatic, aromatic and heteroaromatic amines efficiently undergoes the N-tert-butyloxycarbonylation under the developed protocol. The aminoalcohol, aminophenol, aminoester as well as various chiral amines underwent the chemoselective N-Boc protection under the optimized reaction condition. The rapid reaction rate, mild conditions, very good functional group tolerance, excellent yield, solvent-free, easy recovery products and excellent catalyst recyclability are the advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.

Green approach to Chemo-Selective N-Boc Protection of Amines using Catalytic amount of Lithium Hydroxide Monohydrate under Solvent Free Condition

<p>The protecting group plays important role in synthesis of multifunctional targets. A simple rapid efficient and green method for chemo-selective N-Boc protection of amines using Lithium hydroxide as a green catalyst. In the present work amine protection in presence of ditert-butyl carbonate under solvent free condition is carried out. An efficient green protocol for chemoselctive N-Boc protection of aryl, aliphatic, aromatic, acyclic and hetero cyclic amines (1 m mol %)( 10, 20, 30) were carried out with ditert-butyl carbonate (Boc)2 O using Lithium hydroxide monohydrate (10 mol %) at room temperature under solvent free condition to give white solid monitored on TLC. No side reactions are observed .The present protocol were simple, rapid, efficient, shorter reaction times, high yielding, highly selective, economical and eco-friendly</p>

Sustainable and chemoselective N-Boc protection of amines in biodegradable deep eutectic solvent

A green and practical approach for the chemoselective N-tert-butyloxycarbonylation of structurally diverse amines with di-tert-butyl dicarbonate (Boc2O) is described. Selective N-Boc protection was achieved in excellent yields in urea-choline chloride deep eutectic solvent (DES) as the most promising environmentally benign and cost-effective solvent under mild reaction condition. DES can protect various aromatic and aliphatic amines using Boc2O in good to excellent yields in short reaction times without any side products.

Efficient N-Boc protection of amines by a reusable heterogeneous solid acid nanocatalyst at room temperature

An efficient and rapid protocol for chemoselective N-Boc protection of various structurally different aryl, aliphatic, and heterocyclic amines is reported with (Boc)2O using mesoporous silica phenylsulfonic acid (SBA-15-Ph-SO3H) as a recyclable and heterogeneous solid acid nanocatalyst under solvent-free condition at ambient temperature. The catalyst can be easily recovered and reused for ten reaction cycles for protection of amines without considerable loss of activity. The advantages of this green method are simplicity, easy workup, chemoselectivity, short reaction time, and excellent yield.

The chemoselective N-Boc protection of amines in the presence of solid-supported perchloric acid as an efficient and reusable solid acid

The chemoselective N-Boc protection of amines has been performed in the presence of catalytic amount of poly(4-vinylpyridinium) perchlorate at room temperature .and neat conditions. This new method has distinct advantages, including its excellent yields and short reaction times as well as being green in terms of avoiding the use of toxic catalysts and solvents. Furthermore, the catalyst can be reused and recycled several times without significant loss in its activity.

Nanocrystalline TiO2–HClO4: A novel, efficient and recyclable catalyst for the chemoselective N-Boc protection of amines under solvent-free conditions

Abstract Nanocrystalline TiO 2 –HClO 4 , as newly reported catalyst, has been used as an efficient and reusable catalyst for the chemoselective N -Boc protection of amines. The clean, mild acidity condition, quantitative yields of products, short reaction time and low reaction temperature are attractive features of this reaction. In practice, this method is a combination of a satisfactory synthesis and more significantly easy product isolation and purification.

Succinimide sulfonic acid (SuSA): an efficient and recyclable catalyst for the chemoselective N-Boc protection of amines

Succinimide sulfonic acid (SuSA) as a stable reagent is easily prepared by the reaction of succinimide with neat chlorosulfonic acid. This compound is able to catalyze the chemoselective conversion of amines to their corresponding N-Boc protected derivatives with (Boc)2O. All reactions were performed under mild conditions, giving the desired products in good to high yields.

An efficient and highly chemoselective N-Boc protection of amines, amino acids, and peptides under heterogeneous conditions

A simple and efficient procedure for chemoselective mono-N-Boc protection of various structurally diverse amines, amino acids, and peptides with di-tert-butyl dicarbonate using Amberlyst-15 as catalyst in ethanol is described. The catalyst can be readily separated from the reaction products with simple filtration and recovered for direct reuse. No competitive side-reactions such as formation of isocyanate, urea, oxazolidinone, and N,N-di-Boc derivatives were observed.

Sulfonic acid-functionalized ordered nanoporous Na+-montmorillonite (SANM): A novel, efficient and recyclable catalyst for the chemoselective N-Boc protection of amines in solventless media

Abstract Sulfonic acid-functionalized ordered nanoporous Na+-montmorillonite (SANM) was used as an efficient catalyst for N-tert-butoxycarbonylation of amines with di-tert-butyl dicarbonate under solvent-free conditions at room temperature. Various aliphatic, aromatic, heterocyclic amines and aminols were protected as their corresponding mono-carbamates in excellent yields and short reaction times. No competitive side reactions such as isocyanate, urea, and N,N-di-Boc formation were observed. The reported method is mild, chemoselective and has the advantages such as heterogeneous catalysis, low cost and the recyclability of the catalyst.

Guanidine hydrochloride as an organocatalyst for N-Boc protection of amino groups

A simple and efficient method for the chemoselective N-Boc protection of the amine moiety in a variety of compounds is described using di- tert-butyl dicarbonate and guanidine hydrochloride as an organocatalyst in ethanol at 35–40 °C. Selective mono- N-Boc protection of diamines and chemoselective protection of hydroxylamines without formation of any side products is achieved. Amino acids and peptides are N-Boc protected efficiently in excellent yields under convenient reaction conditions.

Protic ionic liquid [TMG][Ac] as an efficient, homogeneous and recyclable catalyst for Boc protection of amines

Abstract An efficient and practical protocol for the chemoselective N-Boc protection of various structurally different aryl, aliphatic and heterocyclic amines was carried out with (Boc)2O using protic 1, 1, 3, 3-tetra-methylguanidinium acetate (10 mol%) as recyclable catalyst under solvent free condition at ambient temperature. No competitive side reactions (isocyanate, urea and N, N-di-Boc) were observed. α-Amino alcohols afforded the N-Boc-derivative without oxazolidinone formation.

An efficient and chemoselective Brønsted acidic ionic liquid-catalyzed N-Boc protection of amines

The first report of a Brønsted acidic ionic liquid, 1-methylimidazolium tetrafluoroborate [(HMIm)BF 4], catalyzed efficient and chemoselective N-Boc protection of various amines using (Boc) 2O is presented. Optically pure amino alcohols and amino acid esters were converted efficiently to their corresponding optically pure N-Boc derivatives. The reported method is mild, solvent-free and has the advantages of both homogeneous and heterogeneous catalysis with high product yields, selectivity and ease of product separation.

Efficient, solventless N-Boc protection of amines carried out at room temperature using sulfamic acid as recyclable catalyst

A simple, rapid, and efficient protocol for the chemoselective N-Boc protection of amines using sulfamic acid as catalyst is described. N-Boc protection of various structurally diverse aliphatic, aromatic, alicyclic, and heterocyclic amines (1°, 2°, 3°) was carried out with (Boc) 2O using sulfamic acid as catalyst (5 mol %) at room temperature under solventless conditions. The advantages of this method are simplicity, shorter reaction times (1–15 min), a cost-effective catalyst, and excellent isolated yields (90–100%); it is also environmentally benign. Moreover, the combined use of ultrasound and sulfamic acid achieves a synergic effect that is especially marked in the N-Boc protection of deactivated (sterically hindered and electron-deficient) amines. The catalyst possesses distinct advantages: ease of handling, cleaner reactions, high activity, and excellent chemoselectivity.