Organic Letters
Letter
(1a) with excellent diastereoselectivity. To improve overall
diastereoselectivity of the sequence, alkynol 10m was reacted
under the optimized reaction condition,15 followed by
debenzylation using H2/Pd−C, which afforded ( )-centrolobine
(1) in excellent yield with excellent diastereoselectivity (Scheme
9).16
We are grateful to UGC and CSIR, New Delhi for the award of
research fellowship to D.S.V. and S.K.N.
REFERENCES
■
(1) (a) De Albuquerque, I. L.; Galeffi, C.; Casinovi, C. G.;
MariniBettolo, G. B. Gazz. Chim. Ital. 1964, 287. (b) Galeffi, C.;
Casinovi, C. G.; Marini-Bettolo, G. B. Gazz. Chim. Ital. 1965, 95.
(c) Arango Craveiro, A.; da Costa Prado, A.; Gottlieb, O. R.; Welerson
de Albuquerque, P. C. Phytochemistry 1970, 9, 1869. (d) Jurd, L.; Wong,
R. Y. Aust. J. Chem. 1984, 37, 1127. (e) de C. Alcantara, A. F.; Souza, M.
Scheme 9. Total Synthesis of ( )-Centrolobine (1) and Its
Homologue 1a
R.; Pilo-
(2) Rodriguez, A. D.; Cob
915.
́
Veloso, D. Fitoterapia 2000, 71, 613.
́
ar, O. M.; Padilla, O. L. J. Nat. Prod. 1997, 60,
(3) (a) Kurosawa, E.; Fukuzawa, A.; Irie, T. Tetrahedron Lett. 1973, 14,
4135. (b) Suzuki, M.; Kurata, K.; Kurosawa, E. Bull. Chem. Soc. Jpn.
1986, 59, 2953. (c) Fukuzawa, A.; Masamune, T. Tetrahedron Lett. 1981,
22, 4081.
(4) Penga, G.-P.; Tiana, G.; Huanga, X.-F.; Lou, F.-C. Phytochemistry
2003, 63, 877.
(5) Audouze, K.; Nielsen, E. O.; Peters, D. J. Med. Chem. 2004, 47,
3089.
(6) For reviews on hydroalkoxylation of alkynol: (a) Alonso, F.;
Beletskaya, I. P.; Yus, M. Chem. Rev. 2004, 104, 3079. (b) Wu, X. F.;
Neumann, H.; Beller, M. Chem. Rev. 2013, 113, 1.
(7) (a) Murayama, H.; Nagao, K.; Ohmiya, H.; Sawamura, M. Org. Lett.
2015, 17, 2039. (b) Fujita, S.; Abe, M.; Shibuya, M.; Yamamoto, Y. Org.
Lett. 2015, 17, 3822. (c) Shigehisa, H.; Hayashi, M.; Ohkawa, H.; Suzuki,
T.; Okayasu, H.; Mukai, M.; Yamazaki, A.; Kawai, R.; Kikuchi, H.; Satoh,
Y.; Fukuyama, A.; Hiroya, K. J. Am. Chem. Soc. 2016, 138, 10597.
(d) Ferrand, L.; Tang, Y.; Aubert, C.; Fensterbank, L.; Mouries- Mansuy,
V.; Petit, M.; Amatore, M. Org. Lett. 2017, 19, 2062. For acid mediated
hydroalkoxylation of alkenol: (e) Deka, M. J.; Indukuri, K.; Sultana, S.;
Borah, M.; Saikia, A. K. J. Org. Chem. 2015, 80, 4349. (f) Sultana, S.;
Devi, N. R.; Saikia, A. K. Asian J. Org. Chem. 2015, 4, 1281. For reviews
on hydroalkoxylation of alkene: (g) Patil, N. T.; Kavthe, R. D.; Shinde,
V. S. Tetrahedron 2012, 68, 8079.
In conclusion, we have developed a metal-free, Lewis acid
mediated hydroalkoxylation−reduction cascade of alkynols for
the stereoselective synthesis of cyclic ethers as well as 1,4-
oxazepanes. The strategy was also extended for the synthesis of
oxa-bicyclic scaffolds using alkynols tethered to carbon
nucleophiles. The developed method was applied in the total
synthesis of natural products such as ( )-calyxolane A and B and
( )-centrolobine, as well as its homologue.
(8) (a) Gharpure, S. J.; Shukla, M. K.; Vijayasree, U. Org. Lett. 2009, 11,
5466. (b) Gharpure, S. J.; Reddy, S. R. B. Org. Lett. 2009, 11, 2519.
(c) Gharpure, S. J.; Reddy, S. R. B. Tetrahedron Lett. 2010, 51, 6093.
(d) Gharpure, S. J.; Prasad, J. V. K. Eur. J. Org. Chem. 2013, 2013, 2076.
(9) Gharpure, S. J.; Nanda, S. K.; Padmaja; Shelke, Y. G. Chem. - Eur. J.
2017, 23, 10007.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
■
S
Synthetic procedures and characterization data of
(10) Carreno, M. C.; Des Mazery, R.; Urbano, A.; Colobert, F.;
̃
Solladie, G. J. Org. Chem. 2003, 68, 7779.
Accession Codes
(11) Shibuya, M.; Fujita, S.; Abe, M.; Yamamoto, Y. ACS Catal. 2017,
7, 2848.
graphic data for this paper. These data can be obtained free of
Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: +44 1223 336033.
(12) (a) Hilt, G.; Bolze, P.; Harms, K. Chem. - Eur. J. 2007, 13, 4312.
(b) Liang, X.; Wei, K.; Yang, Y.-R. Chem. Commun. 2015, 51, 17471.
(c) Shuler, W. G.; Combee, L. A.; Falk, I. D.; Hilinski, M. K. Eur. J. Org.
Chem. 2016, 2016, 3335. (d) Zhao, F.; Li, N.; Zhang, T.; Han, Z.-Y.;
Luo, S.-W.; Gong, L.-Z. Angew. Chem., Int. Ed. 2017, 56, 3247.
(13) (a) Barluenga, J.; Fernandez, A.; Dieg
́
uez, A.; Rodríguez, F.;
Fananas, F. J. Chem. - Eur. J. 2009, 15, 11660. (b) Vandavasi, J. K.; Hu,
́
̃
AUTHOR INFORMATION
W. P.; Boominathan, S. S. K.; Guo, B. C.; Hsiao, C. T.; Wang, J. J. Chem.
Commun. 2015, 51, 12435.
■
Corresponding Author
ORCID
(14) (a) Miranda, P. O.; Ramirez, M. A.; Martin, V. S.; Padron, J. I.
Chem. - Eur. J. 2008, 14, 6260. (b) Gharpure, S. J.; Shelke, Y. G.; Kumar,
D. P. Org. Lett. 2015, 17, 1926 and the references cited therein.
(15) For the detailed procedure of the synthesis of alkynol 10m, see
(16) For total synthesis of centrolobine, see: (a) Nagarjuna, B.;
Thirupathi, B.; Rao, C. V.; Mohapatra, D. K. Tetrahedron Lett. 2015, 56,
4916. (b) Latif, M.; Yun, J. I.; Seshadri, K.; Kim, H. R.; Park, C. H.; Park,
H.; Kim, H.; Lee, J. J. Org. Chem. 2015, 80, 3315 and the references cited
therein.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank SERB, New Delhi for financial support. We thank Mr.
Darshan Mhatre of the X-ray facility of the Department of
Chemistry, IIT Bombay for collecting the crystallographic data.
D
Org. Lett. XXXX, XXX, XXX−XXX