N. Lu et al. / Tetrahedron 72 (2016) 3468e3476
3475
Esters 1e15 exhibited spectroscopic data exactly identical to those
O]CCHe), 1.71 (hex, 2H, J¼6.8 Hz, CH2e), 1.54e1.28 (m, 20H,
CH2e), 1.16 (d, 6H, J¼6.8 Hz, CH3).
reported in the literature.15,28e34
C
12H23OC(O)CH(CH3)2, GC/MS (m/z; EI): 254 (Mþ), 211
4.7.1. (a)15 Ester 1 (Cyclohexyl acetate): colorless liquid. 1H NMR
(MþꢂjꢂC3H7), 167 (MþeC4H7O2), 71 (C4H7Oþ), 43 (C3Hþ7 ).
(500 MHz, CDCl3)
d 4.72 (m, H, OCHe), 2.01 (s, 3H, CH3), 1.87e1.85
(m, 2H, CHe), 1.75e1.71 (m, 2H, CHe), 1.57e1.54 (m, 2H, CH2e),
1.45e1.22 (m, 4H, CH2e).
4.7.9. (i)34 Ester 9 (4-nitrophenyl acetate): pale yellow solid, m.p:
77 ꢀC. 1H NMR (500 MHz, CDCl3)
d
8.25 (d, 2H, J¼8.7 Hz, C6H4e),
C6H11OC(O)CH3, GC/MS (m/z; EI): 142 (Mþ), 99 (MþeC2H3O), 83
(MþeC2H3O2), 43 (C2H3Oþ).
7.26 (d, 2H, J¼8.7 Hz, C6H4e), 2.32 (s, 3H, CH3).
4-NO2PhOC(O)CH3, GC/MS (m/z; EI): 181 (Mþ), 138
(MþeC2H3O), 122 (MþeC2H3O2), 92 (MþeC2H3NO3), 43 (C2H3Oþ).
4.7.2. (b)28 Ester 2 (Cyclohexyl isobutyrate): colorless liquid. 1H
NMR (500 MHz, CDCl3)
d
4.71 (m, H, OCHe), 2.46 (sept, H, J¼6.8 Hz,
4.7.10. (j)26 Ester 10 (4-nitrophenyl isobutyrate): pale yellow solid,
O]CCHe), 1.83e1.78 (m, 2H, CHe), 1.72e1.68 (m, 2H, CHe),
1.53e1.49 (m, 2H, CH2e), 1.44e1.23 (m, 4H, CH2e), 1.11 (d, 6H,
J¼6.8 Hz, CH3).
m.p: 39.4 ꢀC. 1H NMR (500 MHz, CDCl3)
d
8.26 (d, 2H, J¼8.6 Hz,
C6H4e), 7.25 (d, 2H, J¼8.6 Hz, C6H4e), 2.81 (sept, H, J¼6.8 Hz, O]
CCHe), 1.30 (d, 6H, J¼6.8 Hz, CH3).
C6H11OC(O)CH(CH3)2, GC/MS (m/z; EI): 170 (Mþ), 127
(MþꢂjꢂC3H7), 99 (MþeC4H7O), 83 (MþeC4H7O2), 71 (C4H7Oþ), 43
(C3Hþ7 ).
4-NO2PhOC(O)CH(CH3)2, GC/MS (m/z; EI): 209 (Mþ), 138
(MþeC4H7O), 122 (MþeC4H7O2), 92 (MþeC2H3NO3), 71 (C4H7Oþ),
43 (C3Hþ7 ).
4.7.3. (c)29 Ester 3 (1-phenylethyl acetate): colorless liquid. 1H
4.7.11. (k)26 Ester 11 (dimethylbenzyl acetate): colorless liquid. 1H
NMR (500 MHz, CDCl3)
d
7.33 (m, 4H, C6H5-), 7.27 (m, H, C6H5e), 5.88
NMR (500 MHz, CDCl3)
d
7.38 (m, 4H, C6H5e), 7.28 (t, H, J¼6.8 Hz,
(q, H, J¼6.8 Hz, OCHe), 2.05 (s, 3H, CH3), 1.53 (d, 3H, J¼6.8 Hz, CH3).
PhCH(CH3)OC(O)CH3, GC/MS (m/z; EI): 164 (Mþ), 121
(MþeC2H3O), 105 (MþeC2H3O2), 77 (MþeC4H7O2), 43 (C2H3Oþ).
C6H5e), 2.07 (s, 3H, CH3), 1.82 (s, 6H, CH3).
PhCH(CH3)2OC(O)CH3, GC/MS (m/z; EI): 178 (Mþ), 135
(MþeC2H3O), 119 (MþeC2H3O2), 91 (MþeC4H7O2), 77
(MþeC5H9O2), 43 (C2H3Oþ).
4.7.4. (d)30 Ester 4 (1-phenylethyl isobutyrate): colorless liquid. 1H
NMR (500 MHz, CDCl3)
d
7.33 (m, 4H, C6H5e), 7.27 (m, H, C6H5e),
4.7.12. (l)26 Ester 12 (dimethylbenzyl isobutyrate): pale yellow
5.87 (q, H, J¼6.8 Hz, OCHe), 2.57 (sept, H, J¼6.8 Hz, O]CCHe), 1.53
(d, 3H, J¼6.8 Hz, CH3), 1.19 (d, 3H, J¼7.1 Hz, CH3), 1.17 (d, 3H,
J¼7.1 Hz, CH3).
solid, m.p: 72.4 ꢀC. 1H NMR (500 MHz, CDCl3)
d 7.38 (m, 4H, C6H5e),
7.27 (t, H, J¼6.8 Hz, C6H5e), 2.57 (sept, H, J¼6.8 Hz, O]CCHe), 1.81
(s, 6H, CH3), 1.20 (d, 6H, J¼6.8 Hz, CH3).
PhCH(CH3)OC(O)CH(CH3)2, GC/MS (m/z; EI): 192 (Mþ), 121
(MþeC4H7O), 105 (MþeC4H7O2), 77 (MþꢂjꢂC6H11O2), 43 (C3Hþ7 ).
PhCH(CH3)2OC(O)CH(CH3)2, GC/MS (m/z; EI): 206 (Mþ), 135
(MþeC4H7O), 119 (MþeC4H7O2), 91 (MþꢂjꢂC6H11O2), 71 (C4H7Oþ),
43 (C3Hþ7 ).
4.7.5. (e)31 Ester
colorless liquid. 1H NMR (500 MHz, CDCl3)
5
(2-isopropyl-5-methylcyclohexyl acetate):
4.60 (dt, H, J¼4.3 Hz
d
4.7.13. (m) Ester 13 (3-pyridinylmethyl acetate): pale yellow liq-
and 11.1 Hz, OCHe), 1.95 (s, 3H, CH3), 1.92 (d, H, J¼11.9 Hz, CHe),
1.79 (dsept, H, J¼2.6 Hz and 6.8 Hz, CHe), 1.63e1.57 (m, 2H, CH2e),
1.44e1.37 (m, H, CHe), 1.28 (tt, H, J¼2.6 Hz and 11.1 Hz, CHe), 0.99
(dq, H, J¼3.4 Hz and 9.4 Hz, CHe), 0.88 (q, H, J¼11.1 Hz, CHe), 0.83
(d, 3H, J¼3.4 Hz, CH3), 0.82 (d, 3H, J¼3.4 Hz, CH3), 0.81 (m, H, CHe),
0.69 (d, 3H, J¼7.7 Hz, CH3).
uid. 1H NMR (500 MHz, CDCl3)
d 8.53 (s, H, C5H4Ne), 8.48 (d, H,
J¼4.3 Hz, C5H4Ne), 7.60 (d, H, J¼7.9 Hz, C5H4Ne), 7.20 (dd, H,
J¼7.3 Hz and 4.9 Hz, C5H4Ne), 5.02 (s, 2H, CH2OC]O), 1.99 (s, 3H,
O]CCH3).
C5H4NCH2OCOCH3, GC/MS (m/z; EI): 151 (Mþ),108 (MþeC2H3O),
92 (MþeC2H3O2), 78 (MþeC3H5O2), 43 (C2H3Oþ).
2-CH(CH3)2-5-CH3C6H9OC(O)CH3, GC/MS (m/z; EI): 198 (Mþ),
139 (MþeC2H3O2), 124 (MþeC3H6O2), 96 (MþꢂjꢂC5H10O2), 81
(MþeC6H13O2), 43 (C2H3Oþ).
Acknowledgements
N. Lu thanks National Taipei University of Technology and the
Ministry of Science and Technology of Taiwan (MOST 104-2113-M-
027-004-MY1) for the financial supports.
4.7.6. (f) Ester 6 (2-isopropyl-5-methylcyclohexyl isobutyrate):
colorless liquid. 1H NMR (500 MHz, CDCl3)
d 4.60 (m, H, OCHe), 2.43
(sept, H, J¼6.8 Hz, O]CCHe), 1.89 (d, H, J¼11.9 Hz, CHe), 1.81
(dsept, H, J¼2.6 Hz and 6.8 Hz, CHe), 1.63e1.57 (m, 2H, CH2e),
1.43e1.39 (m, H, CHe), 1.31 (tt, H, J¼2.6 Hz and 11.1 Hz, CHe), 1.08
(d, 3H, J¼3.4 Hz, CH3), 1.07 (d, 3H, J¼3.4 Hz, CH3), 0.98 (dq, H,
J¼3.4 Hz and 9.4 Hz, CHe), 0.87 (q, H, J¼11.1 Hz, CHe), 0.83 (d, 3H,
J¼3.4 Hz, CH3), 0.81 (d, 3H, J¼3.4 Hz, CH3), 0.75 (m, H, CHe), 0.68 (d,
3H, J¼6.8 Hz, CH3).
Supplementary data
Supplementary data associated with this article can be found in
References and notes
2-CH(CH3)2-5-CH3C6H9OC(O)CH(CH3)2, GC/MS (m/z; EI): 226
(Mþ), 139 (MþeC4H7O2), 124 (MþeC5H10O2), 96 (MþꢂjꢂC7H14O2),
81 (MþeC8H17O2), 71 (C4H7Oþ), 43 (C3Hþ7 ).
Baker, D. E.; Osburn, P. L..; Wilson, A. and Sink, E. M.. J. Am. Chem. Soc. 2000,
9058e9064.
4.7.7. (g)32 Ester 7 (cyclododecyl acetate): colorless liquid. 1H NMR
(500 MHz, CDCl3)
d 5.02 (m, H, OCHe), 2.04 (s, 3H, CH3), 1.72 (hex,
ꢁ
ꢁ
2H, J¼6.8 Hz, CH2e), 1.52e1.29 (m, 20H, CH2e).
C
12H23OC(O)CH3, GC/MS (m/z; EI): 226 (Mþ), 167 (MþeC2H3O2),
43 (C2H3Oþ).
4.7.8. (h)33 Ester 8 (cyclododecyl isobutyrate): colorless liquid. 1H
NMR (500 MHz, CDCl3)
d
5.01 (m, H, OCHe), 2.51 (sept, H, J¼6.8 Hz,