Organic Letters
Letter
and Research (IISER), Bhopal is gratefully acknowledged. We
thank Dr. Rahul Banerjee and Mr. Saibal Bera (CSIRNational
Chemical Laboratory, Pune) for helping us with single-crystal X-
ray diffraction analysis. S.B. thanks UGC for the award of Senior
Research Fellowship (SRF).
Scheme 5. Product Modifications
REFERENCES
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(1) For selected reviews on 1,2-difunctionalizations of C−C multiple
bonds, see: (a) Parry, J. B.; Fu, N.; Lin, S. Synlett 2018, 29, 257.
(b) Wang, X.; Studer, A. Acc. Chem. Res. 2017, 50, 1712. (c) Koike, T.;
Akita, M. Acc. Chem. Res. 2016, 49, 1937. (d) Besset, T.; Poisson, T.;
Pannecoucke, X. Eur. J. Org. Chem. 2015, 2015, 2765. (e) Romero, R.
a
Reaction conditions: phenyl acetylene, 2 mol % Pd(PPh3)2Cl2, 5
b
mol % CuI, Et3N, DCE, 60 °C, 4 h. Reaction conditions: 10 mol %
c
PtCl2, toluene, 70 °C, 4 h. Reaction conditions: TBAF (1 M/THF),
d
̈
̃
M.; Woste, T. H.; Muniz, K. Chem. - Asian J. 2014, 9, 972. (f) Zhu, Y.;
Cornwall, R. G.; Du, H.; Zhao, B.; Shi, Y. Acc. Chem. Res. 2014, 47,
3665.
THF, rt, 2 h. Reaction conditions: 5 mol % Ph3PAuCl, 15 mol %
e
phen, TIPS-EBX, MeCN:1,4-dioxane (3:1), 60 °C, 12 h. Reaction
conditions: K2CO3, EtOH, 75 °C, 12 h.
(2) For recent reviews on the influence of transition-metal catalysis
onto 1,2-difunctionalizations, see: (a) Zhang, J.-S.; Liu, L.; Chen, T.;
Han, L.-B. Chem. - Asian J. 2018, 13, 2277. (b) Yoshida, H. ACS Catal.
2016, 6, 1799. (c) Yin, G.; Mu, X.; Liu, G. Acc. Chem. Res. 2016, 49,
2413. (d) Shimizu, Y.; Kanai, M. Tetrahedron Lett. 2014, 55, 3727.
(e) Beccalli, E. M.; Broggini, G.; Gazzola, S.; Mazza, A. Org. Biomol.
Chem. 2014, 12, 6767. (f) McDonald, R. I.; Liu, G.; Stahl, S. S. Chem.
Rev. 2011, 111, 2981.
(3) For reports on oxyalkynylations, see: (a) Li, Y.; Lu, R.; Sun, S.; Liu,
L. Org. Lett. 2018, 20, 6836. (b) Han, W.-J.; Wang, Y.-R.; Zhang, J.-W.;
Chen, F.; Zhou, B.; Han, B. Org. Lett. 2018, 20, 2960. (c) Orcel, U.;
Waser, J. Angew. Chem., Int. Ed. 2015, 54, 5250. (d) Nicolai, S.; Sedigh-
Zadeh, R.; Waser, J. J. Org. Chem. 2013, 78, 3783. (e) Nicolai, S.; Waser,
J. Org. Lett. 2011, 13, 6324.
the ESI) obtained by desilylation of 3a, derived 1,3-diyne 5b in
62% yield.7b Ester 3a could be readily hydrolyzed, affording the
β-alkynylated allylic alcohol 5c in 77% yield.10b
In conclusion, we have discussed the first gold-catalyzed 1,2-
oxyalkynylation of N-allenamides with proper atom-economical
usage of ethylnylbenziodoxolones (EBXs) offering direct access
to 1,3-enynes under mild conditions. Such straightforward
assembly of 1,3-enynes via β-alkynylations of N-allenamides
have been rarely explored. As evidenced by tandem mass
spectrometry analysis, redox-neutral gold catalysis was found to
be instrumental in the reaction. Indeed, the usefulness of the
method is amplified with further viable manipulations of the
resulting scaffold, considering its unique reactive features. More
importantly, by offering two concomitant functionalizations
from a single EBX reagent, the current methodology creates new
opportunities for streamlined reaction design.
(4) Huang, L.; Rudolph, M.; Rominger, F.; Hashmi, A. S. K. Angew.
Chem., Int. Ed. 2016, 55, 4808.
(5) For general reviews for EBX, see: (a) Hari, D. P.; Nicolai, S.;
Waser, J. Patai’s Chemistry of Functional Groups; John Wiley & Sons,
L t d . : C h i c h e s t e r , U . K . , 2 0 1 8
(c) Li, Y.; Hari, D. P.; Vita, M. V.; Waser, J. Angew. Chem., Int. Ed.
2016, 55, 4436. (d) Kaschel, J.; Werz, D. B. Angew. Chem., Int. Ed. 2015,
54, 8876. (e) Brand, J. P.; Waser, J. Chem. Soc. Rev. 2012, 41, 4165.
(6) An alternative oxidative mechanism, however, has not been ruled
out with certainty in many of the cases. For selected recent reports, see:
(a) Peng, S.; Wang, Z.; Zhang, L.; Zhang, X.; Huang, Y. Nat. Commun.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
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S
All experimental procedures, analytical data, and copies of
1H and 13C NMR spectra of all newly synthesized
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́
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2018, 9, 375. (b) Szekely, A.; Peter, A.; Aradi, K.; Tolnai, G. L.; Novak,
Z. Org. Lett. 2017, 19, 954. (c) Brand, J. P.; Chevalley, C.; Scopelliti, R.;
Waser, J. Chem. - Eur. J. 2012, 18, 5655. (d) Boobalan, R.; Gandeepan,
P.; Cheng, C.-H. Org. Lett. 2016, 18, 3314. (e) Xie, F.; Qi, Z.; Yu, S.; Li,
X. J. Am. Chem. Soc. 2014, 136, 4780. (f) Collins, K. D.; Lied, F.;
Glorius, F. Chem. Commun. 2014, 50, 4459. (g) Shen, K.; Wang, Q.
Chem. Sci. 2017, 8, 8265. (h) Jia, K.; Zhang, F.; Huang, H.; Chen, Y. J.
Am. Chem. Soc. 2016, 138, 1514. (i) Chen, F.; Hashmi, A. S. K. Org. Lett.
2016, 18, 2880.
Accession Codes
crystallographic data for this paper. These data can be obtained
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(7) For redox-neutral gold catalysis in EBX chemistry, see: (a) Li, X.;
Xie, X.; Sun, N.; Liu, Y. Angew. Chem., Int. Ed. 2017, 56, 6994.
(b) Banerjee, S.; Patil, N. T. Chem. Commun. 2017, 53, 7937.
(8) (a) Li, Y.; Brand, J. P.; Waser, J. Angew. Chem., Int. Ed. 2013, 52,
AUTHOR INFORMATION
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6743. (b) Nicolai, S.; Erard, S.; Gonzalez, D. F.; Waser, J. Org. Lett.
2010, 12, 384.
Corresponding Author
ORCID
(9) Lu, B.; Wu, J.; Yoshikai, N. J. Am. Chem. Soc. 2014, 136, 11598.
(10) (a) Hari, D. P.; Waser, J. J. Am. Chem. Soc. 2017, 139, 8420.
(b) Hari, D. P.; Waser, J. J. Am. Chem. Soc. 2016, 138, 2190.
(11) For leading reviews on N-allenamides, see: (a) Lu, T.; Lu, Z.; Ma,
Z.-X.; Zhang, Y.; Hsung, R. P. Chem. Rev. 2013, 113, 4862. (b) Wei, L.-
L.; Xiong, H.; Hsung, R. P. Acc. Chem. Res. 2003, 36, 773. For domino
cyclization−alkynylation reactions with alleneyl ketones, see: (c) Ghari,
H.; Li, Y.; Roohzadeh, R.; Caramenti, P.; Waser, J.; Ariafard, A. Dalton
Trans. 2017, 46, 12257. For the first gold-catalyzed reactions of such
nucleophilic and electrophilic allenes, see: (d) Hashmi, A. S. K.;
Schwarz, L.; Choi, J.-H.; Frost, T. M. Angew. Chem., Int. Ed. 2000, 39,
2285. For leading general reviews, see: (e) Yang, W.; Hashmi, A. S. K.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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Generous financial assistance by the Board of Research in
Nuclear Sciences (BRNS), Mumbai (Grant No. 37(2)/14/12/
2015/BRNS/10549), and Indian Institute of Science Education
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