First application of the Dakin-West reaction to fmoc chemistry: Synthesis of the ketomethylene tripeptide fmoc-Nα-Asp(tBu)-(R,S Tyr(tBu)Ψ(CO-CH2)Gly-OH

Synthesis of tert-Butyl 1,3-Diaryl-3-oxopropylcarbamates by a Regiocontrolled Reduction of Ketoaziridines

“…Based on the well-documented transformation of Nacyl-or N-Boc-substituted aziridines into oxazolines in the literature [31][32][33][34] and our success 20,21 with the ring-expansion reaction of N-acyl-substituted aziridines with sodium iodide, we envisioned that ring expansion of 1a with (Boc) 2 O in the presence of sodium iodide might be similarly achieved to give oxazolidin-2-one 6a in a one-pot reaction. Thus, we examined the reaction of aziridine 1a with (Boc) 2 O in the presence of sodium iodide in acetone for achieving this aim; however, no reaction occurred, even under refluxing conditions (Table 1, entry 5).…”

“…Thus, we examined the reaction of aziridine 1a with (Boc) 2 O in the presence of sodium iodide in acetone for achieving this aim; however, no reaction occurred, even under refluxing conditions (Table 1, entry 5).…”

“…The reductive ring opening of aziridines is a synthetically useful transformation for the preparation of amino compounds, especially in the synthesis of β-amino ketones, 1,2 which are important for the synthesis of biologically active compounds. [3][4][5][6][7] Several methods are known for the synthesis of β-amino ketones from the ring opening of aziridines.…”

“…[28][29][30] So, our first aim was to synthesize N-Boc-substituted ketoaziridines as a precursor for preparation of the corresponding nitrogen-containing compounds via ring opening or ring enlargement. At first, we investigated the reaction of ditert-butyl dicarbonate [(Boc) 2 O] and 2-(4-chlorobenzoyl)-3-(4-chlorophenyl)aziridine (1a) in chloroform, acetonitrile, ethanol or acetone in the presence of triethylamine. The mixture was stirred for 10 hours under refluxing conditions, but 1a was recovered unchanged (Table 1, entries 1-4); none of the desired product was detected.…”

“…[3][4][5][6][7] Several methods are known for the synthesis of β-amino ketones from the ring opening of aziridines. A literature survey shows the few reducing agents, including Raney nickel in ethanol, 8 Pearlman's catalyst [Pd(OH) 2 /C], 9 Adam's catalyst (PtO 2 /HCO 2 H), 10 sodium borohydride, 11 tributyltin hydride, 12 poly(methylhydrosiloxane) (PMHS), 13 silyllithium reagents, 14 magnesium 15 and lithium 16 metal reagents, titanium tetraiodide, 17 samarium(II) iodide 18 and visible-light photoredox ruthenium catalysts, 19 for the reductive ring opening of aziridines. None of these methods, however, result in a direct reduction reaction of N-H aziridines to give derivatives of β-carbamato ketones.…”