Catalytic β-Bromohydroxylation of Natural Terpenes: Useful Intermediates for the Synthesis of Terpenic Epoxides

Table 2

Effect of NBS amount on bromohydroxylation of 1a.

Entry	NBS (equiv.)	Conversion (%)	Yield of 2a (%)
1	1	61	54
2	1.1	69	56
3	1.3	76	70
4	1.4	89	67
5	1.5	95	68
6	1.6	98	68
7	1.7	100	57
8	2	100	43

Reaction conditions: 1a 0.4 g, NBS, catalyst (Dowex Marathon A, Cl⁻ form) 0.04 g, 5 mL acetone/H₂O 4 : 1 (v/v), r.t., 15 min. Conversion and yield were calculated by GC using dodecane as the internal standard.