Zinc‐Catalyzed Selective Reduction of Cyclic Imides with Hydrosilanes: Synthesis of ω‐Hydroxylactams

Abstract

Cyclic imides were selectively reduced to the corresponding w-hydroxylactams in high yields with (EtO) 3 SiH (triethoxysilane) or PMHS (polymethylhydrosiloxane) under catalysis of zinc diacetate dehydrate [Zn(OAc) 2 ·2 H 2 O] (10%) and tetramethylethylenediamine (TMEDA) (10%). This catalytic protocol showed good functional group tolerance as well as excellent regioselectivity for unsymmetrical imides bearing coordinating groups adjacent to the carbonyl.

Size‐selective DNA separation: Recovery spectra help determine the sodium chloride (NaCl) and polyethylene glycol (PEG) concentrations required

“…2‐Benzyl‐3‐hydroxyoctahydro‐1 H ‐4,7‐methanoisoindol‐1‐one (2h): 20 White solid; yield: 632.9 mg (2.5 mmol, 82%); mp 148.5–157.1 °C; 1 H NMR (400 MHz, CDCl 3 ): δ =7.32–7.26 (m, 5 H), 5.08–5.04 (m, 1 H), 4.80 (d, J =14.8 Hz, 1 H), 4.25 (d, J =14.8 Hz, 1 H), 2.85–2.81 (m, 1 H), 2.70–2.63 (m, 2 H), 2.51–2.45 (m, 1 H), 2.35–2.33 (m, 1 H), 1.78–1.73 (m, 1 H), 1.62–1.59 (m, 1 H), 1.55–1.47 (m, 4 H); 13 C NMR (100 MHz, CDCl 3 ): δ =174.5, 136.9, 128.7, 128.6, 127.5, 81.7, 48.6, 44.1, 43.5, 41.7, 40.1, 38.8, 25.3, 24.3.…”

“…Ethyl 4‐(1‐hydroxy‐3‐oxoisoindolin‐2‐yl)butanoate (2k): 20 Pale yellow oil; yield: 710.9 mg (2.7 mmol, 90%); 1 H NMR (400 MHz, CDCl 3 ): δ =7.68–7.66 (m, 1 H), 7.61–7.54 (m, 2 H), 7.48–7.44 (m, 1 H), 5.78 (d, J =10.8 Hz, 1 H), 4.00 (q, J =7.2 Hz, 2 H), 3.92 (d, J =10.8 Hz, 1 H), 3.60–3.48 (m, 2 H), 2.45–2.31 (m, 2 H), 2.10–1.91 (m, 2 H), 1.18 (t, J =7.2 Hz, 3 H); 13 C NMR (100 MHz, CDCl 3 ): δ =173.6, 167.7, 144.1, 132.2, 131.4, 129.6, 123.4, 123.0, 82.1, 60.6, 38.8, 31.8, 23.7, 14.2.…”

“…3‐(1‐Hydroxy‐3‐oxoisoindolin‐2‐yl)‐ N , N ‐dimethylpropanamide (2m): 20 White solid; yieldf: 655.5 mg (2.6 mmol, 88%); mp 112.1–115.3 °C; 1 H NMR (400 MHz, CDCl 3 ): δ =7.76–7.74 (m, 1 H), 7.60–7.53 (m, 2 H), 7.48–7.44 (m, 1 H), 6.20 (d, J =4.4 Hz, 1 H), 5.88 (d, J =4.4 Hz, 1 H), 3.98–3.85 (m, 2 H), 3.01 (s, 3 H), 2.96 (s, 3 H), 2.94–2.89 (m, 1 H), 2.68–2.61 (m, 1 H); 13 C NMR (100 MHz, CDCl 3 ): δ =172.4, 168.0, 144.2, 132.1, 131.7, 129.4, 123.3, 123.0, 82.6, 37.3, 35.9, 35.7, 32.8.…”

“…There are a few literature examples that explore the chemoselective reduction of imides with hydrosilanes. N ‐Benzylsuccinimide was reduced with Ph 2 SiH 2 catalyzed by RhH(CO)(PPh 3 ) 3 to give the corresponding pyrrolidine,15a the fluoride‐catalyzed hydrosilylation of aryl imides with polymethylhydrosiloxane (PMHS) afforded the lactams,19 and recently we developed a zinc‐catalyzed selective hydrosilylation of imides to access ω‐hydroxylactams 20. However, controlling the chemoselective reduction of cyclic imides by choosing the appropriate hydrosilane and/or catalyst has not been reported.…”

N-Acyliminium Ion Chemistry: Improving the Access to Unsaturated γ-Lactams and Their N-α-Methoxylated Derivatives: Application to an Expeditive Synthesis of (±)-Crispine A

“…15 Typical reducing reagents such as NaBH 4 , 16 DIBAL-H, 17 LiBH 4 , 18 LiEt 3 BH 19 required careful control of temperature and pH to avoid undesired side products. Hydrogenation with Co or Ru catalysis 20 and Zn catalysis with hydroxysilane 21 were used more recently. We describe here an alternate practical synthetic route to -lactams 9 ( Table 2).…”