An efficient FeCl₃‐promoted O‐alkyl cleavage of esters to carboxylic acids

Abstract

A reliable and practical procedure for FeCl 3 -promoted ester cleavage has been developed. Lewis acids including TiCl 4 , ZnO and FeCl 3 etc. were investigated as promoters for O-alkyl cleavage of carboxylic acid ester. Under optimal reaction conditions, FeCl 3 (1.5 equiv.) was found to possess the highest activity and efficiently enhanced dealkylation of aryl esters, alkyl esters and aromatic heterocyclic esters to give their corresponding carboxylic acids in 54-98% yield, the method provides a complementary access to dealkylation of ester under neutral condition.

MgI2‐Mediated Chemoselective Cleavage of Protecting Groups: An Alternative to Conventional Deprotection Methodologies

“…[32,33] Moreover,t he cleavage of alloc under palladium-free conditions is unprecedented (Table 1, entries [8][9][10]24), with all amines being generated with excellent conversion and isolated yield. Since Fmoc (entries 1-17), acetamide (entry 29), or ether PGs (entries 14,16,22,23,27) remained unaffected, we observedt hat N-trityl wasa lso cleaved (entry 25), Boc being certainly the most labile N-PGs (entries [19][20][21][22][23]. These resultso pen Scheme1.Selectiver emoval of ethyl ester from Fmoc-Phe-OEt.…”

Photoinduced Carbon Tetrabromide Initiated Aerobic Oxidation of Substituted Toluenes to Carboxylic Acids

“…benzoic acid(2a) 1 : White solid; mp=120-121℃; Rf(50% EA/PE)=0.73; 1 H NM R (500 MHz, Chloroform-d) δ 8.34 -8.02 (m, 2H), 7.71 -7.54 (m, 1H), 7.48 (t, J = 7.9 Hz, 2H). 2,3 : White solid; mp=160-162℃; Rf(50% EA/PE)=0.23; 1 H NMR (500 MHz, Chloroform-d) δ 8.05 (d, J = 6.2 Hz, 2H), 7.49 (d, J = 6.2 Hz, 2H), 1.35 (s, 9H). 1 : White solid; mp=183-184℃; Rf(50% EA/PE)=0.6; 1 HNM R (500 MHz, Chloroform-d) δ 8.06 (d, J = 9.0 Hz, 2H), 6.95 (d, J = 9.0 Hz, 2H), 3.88 (s, 3H).…”

“…2,3 : White solid; mp=160-162℃; Rf(50% EA/PE)=0.23; 1 H NMR (500 MHz, Chloroform-d) δ 8.05 (d, J = 6.2 Hz, 2H), 7.49 (d, J = 6.2 Hz, 2H), 1.35 (s, 9H). 1 : White solid; mp=183-184℃; Rf(50% EA/PE)=0.6; 1 HNM R (500 MHz, Chloroform-d) δ 8.06 (d, J = 9.0 Hz, 2H), 6.95 (d, J = 9.0 Hz, 2H), 3.88 (s, 3H). 4 : White solid; mp=187-189℃; Rf(50% EA/PE)=0.63; 1 5,6 1 : White solid; mp=237-240℃; Rf(50% EA/PE)=0.27; 1 H NM R (500 MHz, Chloroform-d) δ 8.33 (d, J = 8.9 Hz, 1H), 8.27 (d, J = 9.0 Hz, 1H).…”

“…1 : White solid; mp=183-184℃; Rf(50% EA/PE)=0.6; 1 HNM R (500 MHz, Chloroform-d) δ 8.06 (d, J = 9.0 Hz, 2H), 6.95 (d, J = 9.0 Hz, 2H), 3.88 (s, 3H). 4 : White solid; mp=187-189℃; Rf(50% EA/PE)=0.63; 1 5,6 1 : White solid; mp=237-240℃; Rf(50% EA/PE)=0.27; 1 H NM R (500 MHz, Chloroform-d) δ 8.33 (d, J = 8.9 Hz, 1H), 8.27 (d, J = 9.0 Hz, 1H). 2,7 : White solid; mp=219-221℃; Rf(50%EA/PE)=0.37; 1 H NMR (500 MHz, Chloroform-d) δ 8.22 (d, J = 8.2 Hz, 2H), 7.80 (d, J = 8.2 Hz, 2H).…”

“…1 H NMR (500 M Hz, Chloroform-d) δ 8.20 (d, J = 8.5 Hz, 2H), 8.05 (d, J = 8.5 Hz, 2H), 3.05 (q, J = 7.2 Hz, 2H), 1.26 (t, J = 7.2 Hz， 3H).…”