2284
J.-M. Vatèle
Letter
Synlett
References and Notes
(21) In MeCN, several products were formed at the aldehyde forma-
tion stage.
(1) (a) Humphrey, J. M.; Chamberlin, A. R. Chem. Rev. 1997, 97,
2343. (b) Cupido, T.; Tulla-Puche, J.; Spengler, J.; Albericio, F.
Curr. Opin. Drug Discovery Dev. 2007, 10, 768. (c) Wilson, R. M.;
Vadola, P. A.; Stockdill, J. L.; Wu, X.; Li, X.; Park, P. K.; Wang, P.;
Danishefsky, S. J. Angew. Chem. Int. Ed. 2012, 51, 2834.
(2) Ghose, A. K.; Viswanadhan, V. N.; Wendoloski, J. J. J. Colomb.
Chem. 1999, 1, 55.
(22) Appropriate physical and analytical data were obtained for all
new compounds (see Supporting Information).
(23) TEMPO-Oxidative Esterification of Alcohols with HFIP Alco-
hol; General Procedure: To a cooled (0 °C) solution of the
alcohol (1 mmol) in CH2Cl2 (2 mL) were added successively
TEMPO (7.8 mg, 5 mol%), TCCA (278 mg, 1.2 equiv) in portions
and the suspension was stirred until the consumption of the
alcohol (progress of the reaction was monitored by TLC). In the
case of substrates 2g,j–n, NaHCO3 (8 equiv) was added before
the addition of TCCA. HFIP alcohol (210 μL, 2 equiv) and pyri-
dine (320 μL, 4 equiv) were then successively added dropwise at
0 °C. After warming, the solution was stirred at r.t. until con-
sumption of the aldehyde (for substrates 1j–n, the oxidative
esterification was conducted at 0 °C). The yellow suspension
was poured onto a small column of silica gel and the HFIP ester
was eluted with petroleum ether or a mixture of petroleum
ether–Et2O.
(3) Valeur, E.; Bradley, M. Chem. Soc. Rev. 2009, 38, 606; and refer-
ences cited therein.
(4) For a review on the oxidative amidation of aldehydes, see: Allen,
C. L.; Williams, J. M. J. Chem. Soc. Rev. 2011, 40, 3405.
(5) (a) Gunanathan, C.; Ben-David, Y.; Milstein, D. Science 2007,
317, 790. (b) Srimani, D.; Balavaman, E.; Hu, P.; Ben-David, Y.;
Milstein, D. Adv. Synth. Catal. 2013, 355, 2525.
(6) For a recent review, see: Chen, C.; Hong, S. H. Org. Biomol. Chem.
2011, 9, 20.
(7) (a) Yao, H.; Yamamoto, K. Tetrahedron Lett. 2012, 53, 5094.
(b) Wang, G.; Yu, Q.-Y.; Wang, J.; Wang, S.; Chen, S.-Y.; Xu, X.-Q.
RSC Adv. 2013, 3, 21306.
(8) (a) Vatèle, J.-M. Tetrahedron Lett. 2006, 47, 715. (b) Vatèle, J.-M.
Synlett 2006, 2055. (c) Vatèle, J.-M. Synlett 2008, 1785.
(d) Vatèle, J.-M. Synlett 2009, 2143. (e) Vatèle, J.-M. Tetrahedron
2010, 66, 904. (f) Barnych, B.; Vatèle, J.-M. Synlett 2011, 2048.
(g) Vatèle, J.-M. Synlett 2014, 25, 1275. (h) Attoui, M.; Vatèle, J.-
M. Synlett 2014, 25, 2923.
(9) For a recent review on tandem oxidation process (TOP), see:
Jeena, V.; Robinson, R. S. RSC Adv. 2014, 4, 40720.
(10) Tan, B.; Toda, N.; Barbas, C. F. III. Angew. Chem. Int. Ed. 2012, 51,
12538.
(11) Trzupek, L. S.; Go, A.; Kopple, K. D. J. Org. Chem. 1979, 44, 4577.
(12) (a) Sarkar, S.; Studer, A. Org. Lett. 2010, 112, 1992. (b) Ji, M.; Lim,
S.; Jang, H.-Y. RSC Adv. 2014, 4, 28225.
(13) (a) Nakano, A.; Takahashi, K.; Ishihara, J.; Hatakeyama, S. Org.
Lett. 2006, 8, 5357. (b) Fang, X.; Li, J.; Wang, C.-J. Org. Lett. 2013,
15, 3448.
(14) Sarkar, S. M.; Wanzala, E. N.; Shibahara, S.; Takahashi, K.;
Ishihara, J.; Hatakeyama, S. Chem. Commun. 2009, 5907.
(15) Merbouch, N.; Bobbitt, J. M.; Brückner, C. J. Org. Chem. 2004, 69,
5116.
(16) For a study of the mechanism on oxoammonium salt oxidation
of alcohols to esters in the presence of pyridine, see: Bobbitt, J.
M.; Bartelson, A. L.; Bailey, W. F.; Hamlin, T. A.; Kelly, C. B. J. Org.
Chem. 2014, 79, 1055.
(17) Szpilman, A. M.; Pisarevsky, E.; Toledo, H.; Abramovich, A.
Synlett 2012, 2261.
(18) Toledo, H.; Pisarevsky, E.; Abramovich, A.; Szpilman, A. M.
Chem. Commun. 2013, 49, 4367.
1,1,1,3,3,3-Hexafluoropropan-2-yl-5-[(tert-butyldimethylsi-
lyl)oxy]pentanoate (2j): Eluent: PE–Et2O (97:3); yield: 79%;
liquid. 1H NMR (300 MHz, CDCl3): δ = 5.77 (hept, J = 6.2 Hz, 1 H),
3.63 (t, J = 6.1 Hz, 2 H), 2.55 (t, J = 7.4 Hz, 2 H), 1.68–1.93 (m, 2
H), 1.56 (dq, J = 9.9, 6.2 Hz, 2 H), 0.88 (s, 9 H), 0.04 (s, 6 H). 13C
NMR (75 MHz, CDCl3): δ = 170.3, 120.5 (q, J = 282 Hz), 66.3
(sept, J = 35 Hz), 62.3, 33.0, 31.7, 25.8 (3 × C), 21.3, 18.3, –5.5 (2
× C).19F NMR (283 MHz): δ = –73.39 (d, J = 6.1 Hz). HRMS (ESI):
m/z [M + Na]+ calcd for C14H24F6NaO3Si: 405.1291; found:
405.1292.
(24) For selected examples of the use of TCCA/TEMPO in the pres-
ence of NaHCO3 in organic synthesis, see: (a) Brenner, E.;
Baldwin, R. M.; Tamagan, G. Org. Lett. 2005, 7, 937. (b) Chen, X.;
Xiong, F.; Zheng, C.; Li, J.; Chen, F. Tetrahedron 2014, 70, 5794.
(25) Cline, G. W.; Hanna, S. B. J. Am. Chem. Soc. 1987, 109, 3087.
(26) Amide Formation from HFIP Esters; General Procedure: To a
solution of HFIP ester (1 mmol) in MeCN (2 mL) was added the
amine (2 equiv except for allylamine: 3 equiv) and the solution
was stirred at r.t. (at reflux for entries 6 and 7 in Table 2 and
entry 6 in Table 3) for the reaction time indicated in Tables 2
and 3. The solution was concentrated and the amide was sepa-
rated from the excess of amine on a pad of silica gel using a
mixture of petroleum ether–EtOAc as eluent.
5-[(tert-Butyldimethylsilyl)oxy]-N-phenethylpentanamide
(3j): Eluent: PE–EtOAc (2:1); yield: 97%; oil. 1H NMR (300 MHz,
C6D6): δ = 6.92–7.32 (m, 5 H), 5.58 (br s, 1 H), 3.52 (t, J = 6.3 Hz,
2 H), 3.41–3.45 (m, 2 H), 2.65 (t, J = 7.1 Hz, 2 H), 1.93 (t, J = 7.2
Hz, 2 H), 1.64–1.78 (m, 2 H), 1.44–1.57 (m, 2 H), 0.98 (s, 9 H),
0.006 (s, 6 H). 13C NMR (75 MHz, C6D6): δ = 172.3, 139.7, 129.1
(2 × C), 128.8 (2 × C), 126.6, 63.1, 41.0, 36.3, 36.2, 32.8, 26.2 (3 ×
C), 22.6, 18.5, –5.1 (2 × C). HRMS (ESI): m/z [M + H]+ calcd for
(19) Kelly, C. B.; Mercadante, M. A.; Wiles, R. J.; Leadbeater, N. E. Org.
Lett. 2013, 15, 2222.
C
19H34NO2Si: 336.2353; found: 336.2344.
(20) (a) De Luca, L.; Giacomelli, G.; Porcheddu, A. Org. Lett. 2001, 3,
3041. (b) De Luca, L.; Giacomelli, G.; Masala, S.; Porcheddu, A.
J. Org. Chem. 2003, 68, 4999.
For other compounds, see Supporting Information.
20
(27) [α]D +81.5 (c 1, CHCl3) for compound 3m {see ref. 28 for the
(S)-enantiomer [α]D20 –80.8 (c 1, CH2Cl2)}.
(28) Gryko, D.; Lipinski, R. Eur. J. Org. Chem. 2006, 3864.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 2280–2284