Deprotection of sulfonamides using iodotrimethylsilane

Synthesis of Constrained Peptidomimetics Containing 2‐Oxo‐1,3‐oxazolidine‐4‐carboxylic Acids

“…The tripeptide Ts-Ala-Oxd-PheNH 2 (2d) was treated with iodotrimethylsilane [19] to give the deprotected product H-AlaOxd-PheNH 2 (4) in moderate yield, together with a mixture of by-products. As an alternative, treatment of 2d with SmI 2 /pyrrolidine/water, [20] was attempted, but this method gave 4 in only low yield.…”

Hg cathode-free electrochemical detosylation of N,N-disubstituted p-toluenesulfonamides: mild, efficient, and selective removal of N-tosyl group

“…Efforts have also been made to develop new and efficient methods for desulfonylation of conventional benzene-and p-toluenesulfonamides under milder conditions than the classical conditions. Several reagents such as Bu 3 SnH/AIBN, 11 SmI 2 , 12 TMSI, 13 TiCl 4 /Zn, 11b TiCl 4 /mischmetal, 14 TiCl 3 /Li, 15 Mg/MeOH, 16 Me 3 CoLi, Me 3 FeLi and Me 3 MnLi with Mg, 17 Ni(0)acac/i-PrMgCl, 18 photolysis, 19 TBAF, 20 phase-transfer catalyst, 21 alkali metals on silica gel, 22 and microwave irradiation in the presence of acid 23 were found to be applicable for desulfonylation. However, many of these reagents were effective only for arenesulfonamides having an activating group such as a phenyl, acyl, and Boc group on nitrogen, and were ineffective for stable amides such as N,N-dialkyltosylamides.…”

Diethoxyphosphoryl as a Protecting-Activating Group in the Synthesis of Polyazacyclophanes

“…Their removal is accomplished by many different procedures, such as by refluxing in strong acids (H 2 SO 4 or HBr), by sodium naphthalenide, lithium aluminum hydride, or Red-Al , by dissolving-metal methods, as well as by photochemical and electrochemical cleavage [5]. Recently, new cleavage methods have been developed, which include the reagents SmI 2 [6], Mg in MeOH [7], Bu 4 NF [8], and Me 3 SiI [9]. Furthermore, many other PGs (e.g., nosylamides [9], 2,4-dinitrobenzenesulfonamides [10], naphthalene-2-sulfonamides [11], tert-butylsulfonamides [12], trifluoroacetamides, carbamates) have already been proposed for the protection of primary amines, keeping in view the sensitivity of the molecule towards the acidic or basic conditions.…”

“…Recently, new cleavage methods have been developed, which include the reagents SmI 2 [6], Mg in MeOH [7], Bu 4 NF [8], and Me 3 SiI [9]. Furthermore, many other PGs (e.g., nosylamides [9], 2,4-dinitrobenzenesulfonamides [10], naphthalene-2-sulfonamides [11], tert-butylsulfonamides [12], trifluoroacetamides, carbamates) have already been proposed for the protection of primary amines, keeping in view the sensitivity of the molecule towards the acidic or basic conditions. All these PGs suffer from one or more disadvantages, such as operationally difficult reaction conditions, long reaction times, expensive precursors, low yields, or contamination of the final product with hardly separable impurities.…”

“…Some of these have previously been prepared by the Richman-Atkins method applied to the nosylamides [9] or tosylamides [1b] [13]. While good yields were reported, the reaction conditions were not favorable for an application of the method to prepare other azacyclophanes embodying different subunits.…”