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

Table 5

Amine effect on the synthesis of epoxide 3a.

Entry	Amine	Conversion (%)	Yield of 3a (%)
1	Aniline	50	0
2	Diethylamine^a	92	82
3	Diethylamine^b	90	87
4	1-Phenylethylamine	71	38
5	1-Phenylethylamine^c	69	31
6	Morpholine	94	48
7	Ammonia	90	33

Reaction conditions: 1a 0.4 g, NBS 1.3 equiv., amine 2 equiv., catalyst (Dowex Marathon A, Cl^-form) 0.04 g, 5 mL acetone/H₂O 4 : 1 (v/v), r.t., 15 min; ^a2 equiv. of diethylamine; ^b3 equiv. of diethylamine; ^c reaction with THF instead of acetone. Conversion and yield were calculated by GC using dodecane as the internal standard.