The Journal of Organic Chemistry
Page 12 of 14
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129.8, 129.2, 128.5, 61.8, 21.2, 19.8; IR (neat): νmax 1725, 1451, 1165 cm-1; m.p. 65-67 °C;
AMM (ESI) m/z calcd for C17H18O2Na+ [M + Na]+ 277.1205, found 277.1210.
1-phenylpropyl benzoate (5e). Ester 5e was synthesized according to the general ester
formation procedure A using MnO2 (237 mg, 2.72 mmol), KH2PO4 (370 mg, 2.72 mmol),
hydrazone 4e (61 mg, 0.41 mmol), benzoic acid (41 mg, 0.34 mmol), and CH2Cl2 (3.4 mL). The
crude product was purified by flash column chromatography (3:97 EtOAc/hexanes) affording
ester 5e (81 mg, 99%) as a yellow oil. Procedure B using MnO2 (251 mg, 2.88 mmol), KH2PO4
(392 mg, 2.88 mmol), hydrazone 4e (64 mg, 0.43 mmol), benzoic acid (44 mg, 0.36 mmol), and
CH2Cl2 (3.6 mL) followed by flash column chromatography as above afforded ester 5e (73 mg,
85%) as a yellow oil. 1H NMR (600 MHz, CDCl3) δ 8.10 (d, J = 7.9 Hz, 2H), 7.56 (t, J = 7.4 Hz,
1H), 7.44 (m, 4H), 7.36 (t, J = 7.6 Hz, 2H), 7.29 (t, J = 7.3 Hz, 1H), 5.93 (t, J = 6.8 Hz, 1H), 2.09
(ddq, J = 14.7, 7.4, 7.4 Hz, 1H), 1.97 (ddq, J = 14.7, 7.4, 7.4 Hz, 1H), 0.98 (t, J = 7.4 Hz, 3H).
Proton NMR data of the product was consistent with the reported literature values.25
1-phenylethyl benzoate (5f). Ester 5f was synthesized according to the general ester formation
procedure A using MnO2 (318 mg, 3.66 mmol), KH2PO4 (498 mg, 3.66 mmol), hydrazone 4f (74
mg, 0.54 mmol), benzoic acid (56 mg, 0.46 mmol), and CH2Cl2 (4.0 mL). The crude product was
purified by flash column chromatography (4:96 EtOAc/hexanes) affording ester 5f (96 mg, 93%)
as a yellow oil. Procedure B using MnO2 (256 mg, 2.94 mmol), KH2PO4 (400 mg, 2.94 mmol),
hydrazone 4f (55 mg, 0.45 mmol), benzoic acid (45 mg, 0.37 mmol), and CH2Cl2 (3.7 mL)
followed by flash column chromatography afforded ester 5f (79 mg, 94%) as a yellow oil. 1H
NMR (600 MHz, CDCl3) δ 8.14 (d, J = 7.1 Hz, 2H), 7.58-7.56 (t, J = 7.4 Hz, 1H), 7.48 (m, 4H),
7.41 (t, J = 7.6 Hz, 2H), 7.34 (t, J = 7.4 Hz, 1H), 6.20 (q, J = 6.6 Hz, 1H), 1.72 (d, J = 6.6 Hz,
3H). Proton NMR data of the product was consistent with the reported literature values.26
1,2,3,4-tetrahydronaphthalen-1-yl benzoate (5g). Ester 5g was synthesized according to the
general ester formation procedure A using MnO2 (210 mg, 2.41 mmol), KH2PO4 (329 mg, 2.41
mmol), hydrazone 4g (58 mg, 0.36 mmol), benzoic acid (36 mg, 0.30 mmol), and CH2Cl2 (3.0
mL). The crude product was purified by flash column chromatography (0:100 to 2:98
EtOAc/hexanes) affording ester 5g (72 mg, 97%) as a yellow oil. Procedure B using MnO2 (247
mg, 2.84 mmol), KH2PO4 (387 mg, 2.84 mmol), hydrazone 4g (68 mg, 0.43 mmol), benzoic acid
(43 mg, 0.36 mmol), and CH2Cl2 (3.6 mL) followed by flash column chromatography as above
afforded ester 5i (75 mg, 84%) as a yellow oil. 1H NMR (600 MHz, CDCl3) 8.10 (d, J = 7.8 Hz,
2H), 7.56 (t, J = 7.4 Hz, 1H), 7.44 (t, J = 7.7 Hz, 2H), 7.40 (d, J = 7.7 Hz, 1H), 7.27 (t, J = 7.4
Hz, 1H), 7.20 (t, J = 8.3 Hz, 2H), 6.30 (t, J = 4.8 Hz, 1H), 2.93-2.89 (m, 1H), 2.90-2.74 (m, 2H),
2.13-2.03 (m, 2H), 1.99-1.82 (m, 1H). Proton NMR data of the product was consistent with the
reported literature values.25
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benzyl cyclohexanecarboxylate (5h). Ester 5h was synthesized according to the general ester
formation procedure A using MnO2 (188 mg, 2.16 mmol), KH2PO4 (294 mg, 2.16 mmol),
hydrazone 4a (40 mg, 0.33 mmol), cyclohexane carboxylic acid (35 mg, 0.27 mmol), and
CH2Cl2 (2.7 mL). The crude product was purified by flash column chromatography (5:95
EtOAc/hexanes) affording ester 5h (56 mg, 95%) as a clear oil. The final product contained up to
17 % of the azine byproduct resulting from hydrazone condensation (1H NMR (600 MHz,
CDCl3) δ 8.69 (d, J = 1.3 Hz, 2H), 7.86-7.83 (m, 4H), 7.34-7.31 (m, 6H)). Procedure B using
MnO2 (226 mg, 2.60 mmol), KH2PO4 (354 mg, 2.60 mmol), hydrazone 4a (77 mg, 0.39 mmol),
cyclohexane carboxylic acid (42 mg, 0.33 mmol), and CH2Cl2 (3.3 mL) followed by flash
column chromatography as above afforded ester 5h (56 mg, 80%) as a clear oil.1H NMR (600
MHz, CDCl3) δ 7.37- 7.28 (m, 5H), 5.10 (s, 2H), 2.35 (tt, J = 11.7, 3.0 Hz, 1H), 1.96-1.90 (m,
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