Interaction of substrate and catalyst during the formation of oxazolidinones from 2-aminoalcohols and diethyl carbonate using recyclable 1,3-dichlorodistannoxanes

An efficient synthesis of oxazolidinone (OXZ) using 2-aminoalcohols (2AAs) and diethyl carbonate (DEC) as reagents in the presence of recyclable catalyst 1,3-dichloro-1,1,3,3-tetraalkyldistannoxane, [(RR′SnCl)2O]2 (1) is reported. 0.5 mol% (with respect to 2AA) of 1 provides OXZ quantitatively within 1 h at 80 °C with turnover frequency (TOF) of 200 h−1. The observed TOF is much higher than the reported value (4 h−1) of the most convenient and commercially feasible K2CO3 catalyst. Chiral 2AAs produce OXZs with 99% ee. Molar dependency of 1, DEC and 2AA is found to be 1:2:2. Molar conductivities (Ω−1 cm2 mol−1) in DMSO at 25 °C are 6.41 for 1a (R = R′ = Bu), 5.25 for 1b (R = Bu, R′ = Ph), 2.87 for 1c (R = Ph, R′ = Bu), and 2.21 for 1d (R = R′ = Ph) which reveal the mobility of bridged Cl in 1 during reaction. The study of a broad range of substrates and reaction parameters supports a reaction pathway that begins with initial attack by –OH of the pre-formed 2-ethylcarbamato aminoalcohol (2ECA) of 2AA on Snb of 1 displacing the bridged Cl. Change in the reaction rates resulted due to various alkyl and aryl substituents on Sn provides better understanding of the distannoxane catalysis, which has not been attempted before for the said reaction.

Synthesis and mechanistic study of oxazolidinone production from 2-aminoalcohol and diethyl carbonate by using [(RR′SnCl)2O]2 as recyclable catalysts are described. Reaction is highly efficient when run for 1 h at 80 °C to obtain 100% yield, >99% ee and TOF of 200 h−1, much higher than the previously reported value of 4 h−1.Figure optionsDownload high-quality image (88 K)Download as PowerPoint slideResearch highlights
► Synthesis and mechanism of oxazolidinone from 2-aminoalcohol and diethyl carbonate.
► Tetrachloro distannoxane catalyst, [(RR′SnCl)2O]2, used is severally recyclable.
► Reaction completes in 1 h at 80 °C with 100% yield and >99% ee.
► Turn over frequency of 200 h−1 is much higher than the reported value of 4 h−1.