| Entry | Catalyst | Remarks | Conversion (%) | Yield of 2a (%) |
| 1 | SiO2 | 60 Å, 70–230 mesh | 79 | 64 | 2 | SIRAL 1 | Al2O3/SiO2 99 : 1, 280 m2/g | 81 | 65 | 3 | Aerosil 300 | SiO2, 300 m2/g | 87 | 51 | 4 | SiZr30 | SiO2/ZrO2 = 30, 573 m2/g | 85 | 62 | 5 | Zeolite beta, H+ form | ZEO cat PBH, SiO2/Al2O3 25–60, 600 m2/g | 83 | 57 | 6 | Ti-SBA15 | SiO2/TiO2 = 30, 668 m2/g | 78 | 61 | 7 | SBA 15 | SiO2, 850 m2/g | 82 | 62 | 8 | TiO2 | Hombikat UV 100 (anatase), 250 m2/g | 81 | 50 | 9 | Zeolite Y, H+ form | CBV 720 (Zeolyst), SiO2/Al2O3 = 30, 780 m2/g, | 86 | 55 | 10 | ZrO2 | Monoclinic phase, (Alfa Aesar), 90 m2/g | 81 | 66 | 11 | CeO2 | Nanopowder (Aldrich), particle size ≤ 25 nm | 82 | 70 | 12 | Dowex Marathon A | Cl− form (Aldrich), 1.3 meq/mL, | 76 | 70 | 13 | Montmorillonite K-10 | Powder, (Aldrich), 250 m2/g | 84 | 58 | 14 | None | | 60 | 40 |
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Reaction conditions: limonene 0.4 g, NBS 1.3 equiv., catalyst 0.04 g, 5 mL acetone/H2O 4 : 1 (v/v), r.t., 15 min. Conversion and yield were calculated by GC analysis using dodecane as the internal standard.
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