Scandium(III)-Catalyzed Enantioselective Allylation of Isatins Using Allylsilanes

Abstract

The scandium(III)-catalyzed enantioselective Hosomi-Sakurai allylation of isatins with various substituted allylic silanes is described. A catalyst loading as low as 0.05 mol % is utilized at room temperature to afford the 3-allyl-3-hydroxy-2-oxindoles in excellent yields and enantioselectivity up to 99% ee, including a demonstration of a gram-scale reaction. The effects of additives and varying silyl groups were explored to demonstrate the scope and application.

Catalytic Stereoselective Synthesis of Diverse Oxindoles and Spirooxindoles from Isatins

“…In the case of the methallylsilane ( 11b , entries 2 and 5), the reaction is run in acetonitrile with TMSCl and NaSbF 6 as additives to increase the efficiency of the reaction and promote in situ deprotection of any resulting OTMS product so that the hydroxy-oxindole products 13 – 15 are obtained exclusively. 10,11 …”

Phosphotungstic Acid as an Efficient Catalyst for Allylation of Isatins and N‐tert‐Butyloxycarbonylamido Sulfones Under Solvent‐Free Conditions

“…Compound 3 a 14: White solid (yield 77.2 mg, 95 %). 1 H NMR (CDCl 3 , 500 MHz,): δ= 7.38–7.4 (d, J =7.5 Hz, 1 H), 7.3–7.33 (t, J =7.5 Hz, 1 H), 7.08–7.11 (t, J =7.5 Hz, 1 H), 6.81–6.83 (d, J =7.5 Hz, 1 H), 5.57–5.65 (m, 1 H), 5.05–5.1 (m, 2 H), 3.75 (br, 1 H), 3.17 (s, 3 H), 2.74–2.77 (m, 1 H), 2.6–2.64 ppm (m, 1 H); 13 C NMR (CDCl 3 , 125 MHz): δ= 177.93, 143.15, 130.49, 129.73, 129.55, 124.06, 123.01, 120.2, 108.31, 75.93, 42.77, 26.09 ppm.…”

“…Compound 3 c 14: White solid (yield 95.5 mg, 90 %). 1 H NMR (CDCl 3 , 500 MHz,): δ= 7.5–7.53 (t, J =8 Hz, 1 H), 7.46–7.47 (d, J =8 Hz, 1 H), 7.37–7.42 (m, 3 H), 7.24–7.27 (m, 1 H), 7.12–7.15 (t, J =8 Hz, 1 H), 6.79–6.81 (d, J =8 Hz, 1 H), 5.62–5.71 (m, 1 H), 5.13–5.18 (m, 2 H), 3.16 (br, 1 H), 2.82–2.86 (m, 1 H), 2.72–2.77 ppm (m, 1 H); 13 C NMR (CDCl 3 , 125 MHz): δ= 177.11, 143.31, 133.98, 130.34, 129.63, 129.25, 128.23, 126.42, 124.24, 123.49, 120.65, 109.65, 76.01, 43.47 ppm.…”

“…Compound 3 e 14: White solid (yield 82 mg, 99 %). 1 H NMR ([D 6 ]DMSO, 500 MHz,): δ= 10.26 (s, 1 H), 7.12–7.13 (m, 1 H), 7–7.04 (m, 1 H), 6.76–6.78 (m, 1 H), 6.12 (s, 1 H), 5.39–5.48 (m, 1 H), 4.94–4.97 (m, 2 H), 2.59–2.63 (m, 1 H), 2.43–2.47 ppm (m, 1 H); 13 C NMR ([D 6 ]DMSO, 125 MHz): δ= 178.61, 158.82, 156.93, 137.65, 133.27, 131.38, 119.13, 115.11, 114.92, 111.94, 111.75, 110.19, 110.13, 75.56, 41.83 ppm.…”

Catalytic Enantioselective Addition of Me2Zn to Isatins

“…Therefore, in the last years, the asymmetric synthesis of chiral 3-substituted-3-hydroxy-2-oxindoles have become a hot topic in organic synthesis [12,13]. The synthesis includes allylation [14,15], crotylation [16], arylation [17,18] and decarboxylative cyanomethylation [19] of isatines, as well as the palladium catalyzed intramolecular arylation [20]. The particular interest is the 3-hydroxy-3-methyl-2-oxindole structure, which is present in several natural products such as convolutamydine C [21] and synthetic compounds with biological activities or drug candidates such as compound 2a [22], compound A [23] and compound B [24] (Figure 1).…”