ChemInform Abstract: An Improved Synthesis of N‐Boc Protected Aryl Amines.

Abstract

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Synthesis of P,N-2,2′-biphenyl derivatives with central chirality

“…2-Bromo and 2-aminobenzeneboronic acids, 2-iodoaniline, 2-aminobiphenyl 3 are commercially available. 2-Iodo-N-(t-butoxycarbonyl)aniline 9b [7], 2-bromo-2′-aminobiphenyl 17 [8], dimesylate 18 [9], 3-N,N-dimethylaminopyrrolidine 14 [10], 1-benzyl-3-(phenylamino)pyrrolidine 26 [11] and 1-Boc-3-(phenylamino)piperidine 28 [11] are known compounds.…”

“…The organic layer was separated and the aqueous layer was extracted with Et 2 O. The combined organic layers were dried over MgSO 4 (2′-Bromo-biphenyl-2-yl)-carbamic acid tert-butyl ester (7) A Schlenk flask, evacuated and backfilled with nitrogen, was charged with Pd(OAc) 2 (196 mg, 5 mol% Pd), triphenylphosphine (945 mg, 20 mol%), dioxane/H 2 O (4:1, 90 mL), 2-iodo-N-(t-butoxycarbonyl)aniline 9b (5.6 g 17.5 mmol), 2-bromobenzeneboronic acid 10 (5.25 g, 26.5 mmol) and Na 2 CO 3 (4.0 g, 38.5 mmol). The flask was evacuated and backfilled with nitrogen then capped with a rubber septum.…”

Molecular Sieves as a New, Highly Efficient, Inexpensive and Reusable Catalyst for N-Ter-Butoxycarbonylation of Amines

“…Aryl amines has reduced nucleophilicity compared to primary or secondary aliphatic amines, due to which BOC protection of aryl amines are not very easy. Existing methods for N-BOC protection has several disadvantages like extended reaction times, elevated temperatures [4], addition of bases like DMAP [5,6], NaOH [7], Pyridine [8], NaHMDS [9]. This is also same in the case of Lewis acid catalysis like LiClO 4 [10], Zn(ClO 4 ) 2 [11], ZrCl 4 [12], sulfamic acids [13], and indium(III) halides [14] are reported for BOC protection of amines.…”

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

“…The base-catalyzed reactions are often associated with the formation of isocyanate [16], urea [10], and N , N -di-Boc derivatives [17]. Moreover, the high toxicity of DMAP and reagents derived from it limits their use [18].…”