4320
J. S. Yadav et al. / Tetrahedron Letters 50 (2009) 4318–4320
Table 1 (continued)
Entry
Substrate
Producta
Time (h)
1.5
Yieldb (%)
75
BnO
O
O
BnO
HO
OH
13b
13
13a
TBSO
O
14a
O
OH
14
1
70
14b
a
Products were characterized by 1H NMR, 13C NMR and mass spectroscopy.
Isolated yields after column chromatography.
b
Table 2
Deprotection of MOM ester with NbCl5 in acetontitrile
Entry
Substrate
Producta
Time (h)
1
Yieldb (%)
OMe
O
O
O
15
91
O
O
OH
15a
15b
OMe
OMeO
O
MeO
MeO
MeO
MeO
16
1
93
O
O
OH
16b
16a
a
Products were characterized by 1H NMR, 13C NMR and mass spectroscopy.
Isolated yields after column chromatography.
b
14. (a) Deville, J. P.; Behar, V. J. Org. Chem. 2001, 66, 4097–4098; (b)
Mohammadpoor-Baltork, I.; Moghadam, M.; Tangestaninejad, S.; Mirkhani,
V.; Mirjafari, A. Polyhedron 2008, 27, 2612–2624.
In conclusion, we have demonstrated the utility of NbCl5 as
a Lewis acid for an efficient cleavage of MOM ether to the cor-
responding alcohol and MOM ester to the corresponding acid.
This protocol with milder reaction conditions (0 °C to room
temperature) and high yield with shorter reaction times may
find wide application in the field of synthetic organic
chemistry.
15. Ramesh, C.; Ravindranath, N.; Das, B. J. Org. Chem. 2003, 68, 7101–7103.
16. Miyake, H.; Tsumara, T.; Sasaki, M. Tetrahedron Lett. 2004, 45, 7213–7215.
17. (a) Yadav, J. S.; Reddy, B. V. S.; Gupta, M. K.; Biswas, S. K. Synthesis 2004, 2711–
2715; (b) Yadav, J. S.; Reddy, B. V. S.; Eeshwaraiah, B.; Reddy, P. N. Tetrahedron
2005, 61, 875–878; (c) Yadav, J. S.; Narsaiah, A. V.; Reddy, B. V. S.; Basak, A. K.;
Nagaiah, K. J. Mol. Catal. A. 2005, 230, 107–111; (d) Yadav, J. S.; Reddy, B. V. S.;
Jaishri Naidu, J.; Sadashiv, K. Chem. Lett. 2004, 33, 926–927; (e) Yadav, J. S.;
Bhunia, D. C.; VamshiKrishna, K.; Srihari, P. Tetrahedron Lett. 2007, 48, 8306–
8310.
Acknowledgements
18. Yadav, J. S.; Bhunia, D. C.; Singh, V. K.; Srihari, P. Tetrahedron Lett, 2009, 50,
Two of us (B.G.) and (D.C.B.) thank CSIR, New Delhi for financial
assistance.
19. Compound 3a was studied with different concentrations of the catalyst.
20. General procedure: To the MOM ether (1 mmol) dissolved in acetonitrile
(3 mL) at 0 °C was added NbCl5 (1 equiv) and stirred against the time
mentioned in the table allowing the reaction mixture to warm to room
temperature. The reaction was monitored by TLC. After completion of the
reaction, the reaction mixture was quenched with satd aq NaHCO3 solution.
The product was extracted with ethyl acetate. The organic layer was washed
with brine, dried over anhydrous Na2SO4 then evaporated to give the crude
product which was purified by silica gel column chromatography. Analytical
References and notes
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data of few examples. 1,3-D
iphenylprop-2-yn-1-ol (9a): Yellow liquid. 1H NMR
(300 MHz, CDCl3): d 2.91 (br s, 1H) 5.64 (s, 1H), 7.22–7.40 (m, 6H), 7.41–7.50
(m, 2H), 7.55–7.63 (m, 2H). 13C NMR (75 MHz, CDCl3): d 64.8, 86.4, 88.7, 122.3,
126.6, 128.1, 128.2, 128.4, 128.5, 131.6, 140.5. IR (neat):
cmax 3385, 3061, 2198,
1488, 1449, 1028, 757, 693 cmÀ1 ESI-MS: m/z 231 (M+Na)+ HRMS for
.
.
C15H12ONa: calcd 231.0780, found 231.0789. (Benzyloxy)propan-1-ol (13a):
Yellow liquid. 1H NMR (300 MHz, CDCl3): d 1.80 (t, J = 5.8 Hz, 2H), 3.34 (br s,
1H), 3.56 (t, J = 5.8 Hz, 2H), 3.66 (t, J = 5.8 Hz, 2H), 4.45 (s, 2H), 7.17–7.39 (m,
5H), 13C NMR (75 MHz, CDCl3): d 31.9, 60.2, 68.1, 72.7, 127.3, 128.1, 137.8. IR
(neat): cmax 3413, 2930, 2862, 1736, 1453, 1364, 1079, 1024, 739 cmÀ1, ESI-
MS: m/z 167 (M+H)+, HRMS for C10H16O2: calcd 167.1066, found 167.1064. 2-
Methoxy-3-methylbenzoic acid (15a): White solid Mp 72 °C. 1H NMR
(300 MHz, CDCl3): d 2.35 (s, 3H), 3.89 (s, 3H), 7.11 (t, J = 7.5 Hz, 1H), 7.38 (d,
J = 7.3 Hz, 1H), 7.85 (d, J = 7.5 Hz, 1H), 11.08 (br s, 1H), 13C NMR (75 MHz,
CDCl3): d 15.8, 61.8, 122.3, 124.3, 130.2, 132.0, 136.5, 158.2, 168.65. IR (neat):
c
max 2949, 2706, 2588, 1701, 1591, 1471, 1305, 1225, 1004, 768 cmÀ1. ESI-MS:
m/z = 167 (M+H)+ HRMS for C9H11O3: calcd 167.0703, found 167.0711.
13. Keith, J. M. Tetrahedron Lett. 2004, 45, 2739–2742.
.