N-tert-Butoxycarbonylation of Structurally Diverse Amines and Sulfamides under Water-Mediated Catalyst-Free Conditions

Abstract

A simple, efficient, and eco-friendly protocol for the N-Boc protection of the amine moiety in a variety of compounds with di-tert-butyl dicarbonate under water-acetone catalyst-free conditions is described. The corresponding monocarbamate is obtained in excellent yields on short reaction times. No competitive side reactions such as isocyanate urea and O-Boc were observed. This method represents a reasonable alternative to the previous reported protection procedures.

A simple and eco-sustainable method for the sulfonylation of amines under microwave-assisted solvent-free conditions

“…22 Introduced by Gedye 23 and Giguere, 24 it has advantages like reduction of reaction times, enhancement of product yields, easy isolation of the nal product, ability to precisely control the temperature, etc. 25 In continuation of our interest towards development of useful green synthetic methodologies, [26][27][28][29][30] we report the successful use of microwave irradiation for the selective sulfonylation of various structurally amines. It is a facile and ecofriendly method for the preparation of sulfonamides wherein the use of solvents and catalysts is avoided.…”

Efficient deprotection of Boc group in amines and sulfamides using Dawson heteropolyacid catalyst

“…In our previous studies [20], we described a convenient access to a series of sulfamides N,N'-disubstituted, (7)(8)(9)(10)(11) starting from amino acids and chlorosulfonylisocyanate in two steps (carbamoyaltion-sulfamoylation). The deprotection protocol giving linear sulfamides (7a-11a) is outlined in Scheme 3.…”

“…The suspension was filtered, the solution was dried over anhydrous Na2SO4, filtered and concentrated under vacuum, (7)(8)(9)(10)(11) The synthesis of the compounds, starting from CSI tertbutyl alcohol and methyl esters of amino acids (Gylcine, Lalanine, L-leucine, and L-phenyalanine) has been previously reported [22,23].…”

“…More recently, we have developed the catalyst-free water-related system for the N-Boc protection/deprotection [9,10]. In the continuity of our research, we have focussed to the development of new reagents and methods for the N-Boc deprotection, we attempt to use the Dawson heteropolyacid (HPA) as catalyst.…”

A Greener Approach for the Chemoselective Boc Protection of Amines Using Sulfonated Reduced Graphene Oxide as a Catalyst in Metal- and Solvent-Free Conditions

“…These catalysts can be easily recovered and recycled. There have also been reports where solvent-free [18][19][20]21,22 or catalyst-free 23,24 conditions have been employed. Looking at the environmental concerns attached with the use of metals, some metal-free 13,19,25 protocols have been reported in the literature.…”