D-aminoacylase-Initiated Cascade Aldol Condensation/Robinson Annulationfor Synthesis ofSubstituted Cyclohex-2-enonesfrom Simple Aldehydes and Acetones
Ziwei Xiang • Yiru Liang • Xiang Chen • Qi Wu* • Xianfu Lin*
Department of Chemistry, Zhejiang University, Hangzhou 310027, P. R. China
E-mail:
Experiment Section
- The catalytic activities of different lipases for the cascade reaction
Table S1. The catalytic activities of different catalysts [a]
Entry / Enzyme / Yield (%) [d]1 / Lipase from C. antarctica (CAL-B) / N.D[e]
2 / Immobilized from Mucor miehei / N.D
3 / Lipase from porcine pancreas (PPL) / Trace
4 / Lipase from hog pancreas (HPL) / Trace
5 / Immobilized penicillin G acylase from Escherichia coli( PGA) / N.D
6 / Lipase from C. cylindracea (CCL) / N.D
7 / D-amanoacylase (DA) / 8
8 / Bovine Serum Albumin (BSA) / N.D
9 / D-amanoacylase denatured with urea[b] / N.D
10 / D-amanoacylase denatured with EDTA[c] / N.D
11 / No catalyst / N.D
[a]Reaction conditions: enzyme (25 mg), p-nitrobenzaldehyde (0.07 mmol), acetone (0.15 ml), octane(1 ml), 50 oC, 48 h.
[b]Pretreated with urea at 100 oC for 8 h.
[c] Pretreated with EDTA at 37 ◦C for 12 h
[d] Yields were determined by HPLC
[e] Not Detected.
- The influence of additive on the cascade reaction
Table S2. The influence of additive on the cascade reaction of 1aand acetone[a]
Entry / Additive / Amount (mmol) / Yield (%)[b]1 / Imidazole / 0.22 / 27
2 / N-methylimidazole / 0.22 / 7
3 / Benzoimidazole / 0.22 / 5
4 / Pyridine / 0.22 / 1
5 / Trimethylamine / 0.22 / 4
6 / 2-Methylimidazole / 0.22 / 10
7 / 4-Nitroimidazole / 0.22 / 2
8 / Acetic Acid / 0.22 / N.D[c]
9 / Imidazole[d] / 0.22 / N.D
[a]Reaction conditions: DA (25 mg), p-nitrobenzaldehyde (0.07mmol), acetone (0.15 ml), octane (1ml), 50 oC, 48 h
[b] Yields were determined by HPLC
[c]Not detected
[d]Without DA
- Preparation of apoenzyme
50mg DA was incubated at 0°C for 12 min in 0.8mL potassium phosphate buffer ( pH 6.5), followed by further incubation at 0°C for 40 min after addition of 10mM EDTA. Then the enzyme solution was dialyzed in cabonate bicarbonate buffer(250 mL, 10 mM, pH 9.3) to remove the metals and reagents, and then lyophilized to produce apoenzyme. The activity of apoenzyme was determined by ninhydrin colorimetric method.
- General procedure for the synthesis of 3a
A suspension of 4-nitrobenzaldehyde (0.7 mmol), acetone (1.5ml) and 100 mg DA in 10 ml dioxane was incubated at 50°C and 200 r.p.m. (orbitally shaken) for 12h. Then the residue was filtered off and the solvent was evaporated. A single product was prepared by silica gel chromatography with an eluent consisting of petroleum/ethylacetate mixtures (v/v: 2:1).
4-hydroxy-4-(4-nitrophenyl)-2-Butanone(3a): Light yellow solid, yield 81%;1H NMR (400 MHz, CDCl3) δ 2.23(s, 3H), 2.86(t, J=5.6 Hz, 2H), 3.58(s, 1H), 5.27(t, 1H, J=6.2 Hz), 7.54(d, 2H, J=8.6 Hz), 8.19(d, 2H, J=8.7 Hz).IR (neat): 3455, 2907, 1714, 1600, 1521, 1341, 1241, 1165, 1079, 858, 839; 13C NMR (400 MHz, CDCl3) δ 208.5, 150.2, 147.3, 126.5, 123.7, 68.9, 51.5, 30.7.
- General procedure for the synthesis of4a
A suspension of p-nitrobenzaldehyde (0.7 mmol), imidazole (0.7 mmol), acetone (1.5ml) and D-aminoacylase 100mg in octane (10ml) was incubated at 50°C and 200 r.p.m. (orbitally shaken) for 12h. Then, solvent was evaporated under vacuum. The crude residue was purified by flash column chromatography on silica gel using petroleum/ethylacetate mixtures (v/v: 5:1).
(3E)-4-(4-nitrophenyl)-3-buten-2-one (4a): Light yellow solid, yield 75%;1H NMR (400 MHz, CDCl3) δ 8.24 (d, J=8.8 Hz, 2H), 7.68 (d, J=8.8 Hz, 2H), 7.53 (d, J=16.0 Hz, 1H), 6.81 (d, J=16.4 Hz, 1H), 2.41 (s, 3H); IR (neat): 1677, 1612, 1525, 1346, 974; 13C NMR (400 MHz, CDCl3) δ 197.4, 148.5, 140.6, 140.0, 130.3, 128.7, 124.1, 27.9.
- General procedure for the synthesis of conjugate cyclohexanone-2-ene
A suspension of 1a-1o (0.7mmol), acetone (1.5ml), 2.1 mmol imidazole and 400 mg D-aminoacylase in 10 mL octane was incubated at 50 oC and shakenfor 48h. After the indicated time, the enzyme was filtered off to terminate the reaction and solvent was evaporated under vacuum. The crude residue was purified by flash chromatography on silica gel using petroleum/ethyl acetate mixtures. Product-containing fractions were combined, concentrated, and dried to give 5a-5n.
- Characterizations for compounds
5a
5-(4’-nitropheny1)-3-methylcyclohex-2-enones5a: CAS No: 62596-10-5;Light yellow solid, m.p. 131-135 oC; 1H NMR (400 MHz, CDCl3) δ 8.23 (d, J=8.8 Hz, 2H), 7.43 (d, J=8.4 Hz, 2H), 6.03 (s, 1H), 3.48-3.42 (m, 1H), 2.71-2.56 (m, 4H), 2.05 (s, 3H); IR (neat): 3060, 3029, 1661, 1606, 1596, 1521, 1346, 853; GC-MS: m/z=231.
5b
5-(3’-nitropheny1)-3-methylcyclohex-2-enones5b:CAS No:10323-98-5;Light yellow solid, m.p. 100-105 oC;1H NMR (400 MHz, CDCl3) δ 8.15-8.13 (m, 2H), 7.60 (d, J=8.0 Hz, 1H), 7.54 (t, J=8.4, 16.4, 8.0 Hz, 1H), 6.02 (s, 1H), 3.52-3.44 (m, 1H), 2.68-2.56 (m, 4H), 2.05 (s, 3H); IR (neat): 3069, 2922, 1662, 1633, 1528, 1352, 887.
5c
5-(4’-fluoropheny1)-3-methylcyclohex-2-enones5c: CAS No: 1222312-10-8; Light yellow solid, m.p. 43-47 oC;1H NMR (400 MHz, CDCl3) δ 7.18 (m, 2H), 7.01 (m, 2H), 5.96 (s, 1H), 3.33-3.25 (m 1H), 2.58-2.46 (m, 4H), 1.99 (s, 3H); IR (neat): 3041, 2916, 1666, 1602, 1511, 1225, 890.
5d
5-(4’-chloropheny1)-3-methylcyclohex-2-enones5d: CAS No: 54795-01-6;Light yellow solid, m.p. 53-55 oC;1H NMR (400 MHz, CDCl3) δ 7.30 (d, J=8.4 Hz, 2H), 7.17 (d, J=8.4 Hz, 2H), 5.97 (s, 1H), 3.34-3.26 (m, 1H), 2.64-2.47 (m, 4H), 2.00 (s, 3H); IR (neat): 3031, 1663, 1633, 1594, 1490, 1379, 827.
5e
5-(2’-chloropheny1)-3-methylcyclohex-2-enones5e: CAS No: 10323-89-4;Light yellow solid, m.p. 61-64 oC;1H NMR (400 MHz, CDCl3) δ 7.33 (d, J=8.0 Hz, 1H), 7.20 (t, J=8.0, 4.0 Hz, 2H), 7.40 (d, J=8.0 Hz, 1H), 5.92 (s, 1H), 3.81-3.73 (m, 1H), 2.59-2.43 (m, 4H), 1.95 (s, 3H); IR (neat): 3058, 1669, 1633, 1612, 1475, 1380, 696, 754.
5f
5-(4’-bromopheny1)-3-methylcyclohex-2-enones5f: CAS No: 211876-67-4;White solid, m.p. 66-69 oC;1H NMR (400 MHz, CDCl3) δ 7.47 (d, J=8.4 Hz, 2H), 7.13 (d, J=8.4 Hz, 2H), 5.99 (s, 1H), 3.33-3.26 (m, 1H), 2.66-2.48 (m, 4H), 2.02 (s, 3H); IR (neat): 3030, 2915, 1663, 1634, 1488, 1379, 890;
5g
5-(2’-bromopheny1)-3-methylcyclohex-2-enones5g:CAS No:10323-92-9; Light yellow solid, m.p. 70-73oC;1H NMR (400 MHz, CDCl3) δ 7.39-7.37 (m, 2H), 7.22-7.14 (m, 2H), 5.96 (s, 1H), 3.34-3.25 (m, 1H), 2.60-2.46 (m, 4H), 2.00 (s, 3H); IR (neat): 3031, 2917, 1664, 1625, 1593, 1430, 888;
5h
5-(4’-cyanopheny1)-3-methylcyclohex-2-enones5h: Light yellow solid, m.p. 55-57 oC;; 1H NMR (400 MHz, CDCl3) δ 7.65 (d, J=8.0 Hz, 2H), 7.37 (d, J=7.6 Hz, 2H), 6.01 (s, 1H), 3.48-3.36 (m, 1H), 2.68-2.51 (m, 4H), 2.03 (s, 3H); IR (neat):3036, 2921, 2227, 1664, 1635, 1608, 1380, 891;13C NMR (400 MHz, CDCl3) δ 24.45, 38.48, 40.38, 43.31, 110.97, 118.55, 126.68, 127.57, 132.60, 148.45, 160.78, 197.73; HRMS [EI]+ Calcd for C14H13NO: 211.0997; found: 211.0996.
5i
5-(2’-cyanopheny1)-3-methylcyclohex-2-enones5i: Light yellow solid, yield 73%; 1H NMR (400 MHz, CDCl3) δ 7.58-7.55 (m, 2H), 7.52-7.45 (m, 2H), 6.01 (s, 1H), 3.43-3.35 (m, 1H), 2.67-2.53 (m, 4H), 2.04 (s, 3H); IR (neat): 3034, 2917, 2229, 1663, 1635, 1602, 1434, 1380, 1251, 888.13C NMR (400 MHz, CDCl3) δ 24.21, 38.18, 40.65, 43.08, 112.95, 118.80, 129.42, 129.81, 130.01, 131.30, 132.60, 144.73, 161.23, 198.04; HRMS [EI]+ Calcd for C14H13NO: 211.0997; found: 211.0999.
5j
5-(4’-trifluoromethylpheny1)-3-methylcyclohex-2-enones5j:CAS No: 1459245-35-2;Light yellow liquid;1H NMR (400 MHz, CDCl3) δ 7.59 (d, J=8.0 Hz, 2H), 7.35 (d, J=8.0 Hz, 2H), 5.99 (s, 1H), 3.44-3.34 (m, 1H), 2.74-2.51 (m, 4H), 2.01 (s, 3H); IR (neat): 3027, 2921, 1667, 1619, 1420, 1326, 1122, 891;
5k
5-pheny1-3-methylcyclohex-2-enones5k: CAS No: 5337-88-2;Light yellow liquid;1H NMR (400 MHz, CDCl3) δ 7.35 (d, J=7.6 Hz, 2H), 7.27 (m, 3H), 6.00 (s, 1H), 3.38-3.30 (m, 1H), 2.68-2.03 (m, 4H), 2.02 (s, 3H); IR (neat): 33081, 3063, 3029, 1663, 1630, 1609, 1496, 1379, 758, 700.
5l
5-(4’-methylpheny1)-3-methylcyclohex-2-enones 5l: CAS No: 5337-88-2; Light yellow liquid; 1H NMR (400 MHz, CDCl3) δ 7.20-7.13 (m, 4H), 5.98 (s, 1H), 3.34-3.26 (m, 1H), 2.63-2.50 (m, 4H), 2.35 (s, 3H), 2.02 (s, 3H); IR (neat): 3024, 2949, 2921, 2853, 1666, 1611, 1568, 1515, 1379, 800.
5o
3-methyl-5-(pyridin-3-yl)cyclohex-2-enone5o: CAS No: 53295-89-9; Light yellow solid,m.p. 60-64 oC;1H NMR (400 MHz, CDCl3) δ 8.54 (s, 1H), 8.52 (d, J=4.4 Hz, 1H), 7.57 (d, J=7.6 Hz, 1H), 7.29 (m, 1H), 6.00 (s, 1H), 3.41-3.33 (m, CH, 1H), 2.64-2.53 (m, 4H), 2.02 (s, 3H); IR (neat): 3032, 2923, 2852, 1667, 1612, 1576, 1549, 1380, 804, 715.
S1