Organic Letters
Letter
McInturff, E. L.; Krische, M. J. Ruthenium(0)-Catalyzed C−C
Coupling of Alkynes and 3-Hydroxy-2-oxindoles: Direct C−H
Vinylation of Alcohols. Org. Lett. 2017, 19, 966.
Piperidines via Cationic Palladium(II)-Catalyzed Reductive Coupling
of N-Tosyl-Tethered Alkynones. Synthesis 2017, 49, 4687.
(8) Wu, W.; Chen, T.; Chen, J.; Han, X. Cationic Palladium(II)-
Catalyzed Reductive Cyclization of Alkynyl Cyclohexadienones. J.
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(9) For selected recent reviews, see: (a) Kaur, K.; Jain, M.; Reddy, R.
P.; Jain, R. Quinolines and Structurally Related Heterocycles as
Antimalarials. Eur. J. Med. Chem. 2010, 45, 3245. (b) Solomon, V. R.;
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Curr. Med. Chem. 2011, 18, 1488. (c) Heterocycles in Natural Products
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(4) For the selected examples of the reductive coupling of allenes,
see: (a) Bower, J. F.; Skucas, E.; Patman, R. L.; Krische, M. J.
Catalytic C-C Coupling via Transfer Hydrogenation: Reverse
Prenylation, Crotylation, and Allylation from the Alcohol or Aldehyde
Oxidation Level. J. Am. Chem. Soc. 2007, 129, 15134. (b) Ngai, M.-Y.;
Skucas, E.; Krische, M. J. Ruthenium Catalyzed C-C Bond Formation
via Transfer Hydrogenation: Branch-Selective Reductive Coupling of
Allenes to Paraformaldehyde and Higher Aldehydes. Org. Lett. 2008,
10, 2705. (c) Han, S.-B.; Kim, I.-S.; Han, H.; Krische, M. J.
Enantioselective Carbonyl Reverse Prenylation from the Alcohol or
Aldehyde Oxidation Level Employing 1,1-Dimethylallene as the
Prenyl Donor. J. Am. Chem. Soc. 2009, 131, 6916. (d) Zbieg, J. R.;
McInturff, E. L.; Krische, M. J. Allenamide Hydro-Hydroxyalkylation:
1,2-Amino Alcohols via Ruthenium-Catalyzed Carbonyl anti-Amino-
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Krische, M. J. Ruthenium Catalyzed Reductive Coupling of
Paraformaldehyde to Trifluoromethyl Allenes: CF3-Bearing All-
Carbon Quaternary Centers. Org. Lett. 2013, 15, 3790. (f) Holmes,
M.; Nguyen, K. D.; Schwartz, L. A.; Luong, T.; Krische, M. J.
Enantioselective Formation of CF3-Bearing All-Carbon Quaternary
Stereocenters via C−H Functionalization of Methanol: Iridium
Catalyzed Allene Hydrohydroxymethylation. J. Am. Chem. Soc.
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(10) For recent reviews on the synthesis of tetrahydroquinolines,
see: (a) Masson, G.; Lalli, C.; Benohoud, M.; Dagousset, G. Catalytic
Enantioselective [4 + 2]-Cycloaddition: A Strategy to Access Aza-
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Nammalwar, B. Recent Syntheses of 1,2,3,4-Tetrahydroquinolines,
2,3-Dihydro-4(1H)-quinolinones and 4(1H)-Quinolinones Using
Domino Reactions. Molecules 2014, 19, 204. (c) Fochi, M.;
Caruana, L.; Bernardi, L. Catalytic Asymmetric Aza-Diels−Alder
Reactions: The Povarov Cycloaddition Reaction. Synthesis 2014, 46,
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(11) For transition-metal-catalyzed enantioselective synthesis of
tetrahydroquinolines, see: (a) Hatano, M.; Mikami, K. Highly
Enantioselective Quinoline Synthesis via Ene-type Cyclization of
1,7-Enynes Catalyzed by a Cationic BINAP-Palladium(II) Complex. J.
Am. Chem. Soc. 2003, 125, 4704. (b) Wang, C.; Tunge, J. A.
Asymmetric Cycloadditions of Palladium-Polarized Aza-o-xylylenes. J.
Am. Chem. Soc. 2008, 130, 8118. (c) Fukamizu, K.; Miyake, Y.;
Nishibayashi, Y. Ruthenium-Catalyzed Enantioselective Carbon-
Carbon Bond Forming Reaction via Allenylidene-Ene Process:
Synthetic Approach to Chiral Heterocycles Such As Chromane,
Thiochromane, and 1,2,3,4-Tetrahydroquinoline Derivatives. J. Am.
Chem. Soc. 2008, 130, 10498. (d) Zhang, X.; Han, X.; Lu, X. Cationic
Pd(II)-Catalyzed Cyclization of N-Tosyl-aniline Tethered Allenyl
Aldehydes with Arylboronic Acids: Diastereo- and Enantioselective
Synthesis of Tetrahydroquinoline Derivatives. Org. Lett. 2015, 17,
3910. (e) Shao, W.; You, S.-L. Highly Diastereo- and Enantioselective
Synthesis of Tetrahydro-5H-Indolo[2,3-b]quinolines through Cop-
per-Catalyzed Propargylic Dearomatization of Indoles. Chem. - Eur. J.
2017, 23, 12489. (f) Chen, H.; Lu, X.; Xia, X.; Zhu, Q.; Song, Y.;
Chen, J.; Cao, W. Asymmetric Catalytic [4 + 2] Cycloaddition via
Cu−Allenylidene Intermediate: Stereoselective Synthesis of Tetrahy-
droquinolines Fused with a γ-Lactone Moiety. Org. Lett. 2018, 20,
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Gonca̧ lves, T. P.; Richardson, J. Cyclometalated Iridium−PhanePhos
Complexes Are Active Catalysts in Enantioselective Allene−Fluoral
Reductive Coupling and Related Alcohol-Mediated Carbonyl
Additions That Form Acyclic Quaternary Carbon Stereocenters. J.
Am. Chem. Soc. 2019, 141, 2087.
(5) For examples of nucleopalladation initiated reactions of alkyne-
tethered ketones or aldehydes, see: (a) Zhao, L.; Lu, X. PdII-Catalyzed
Cyclization of Alkynes Containing Aldehyde, Ketone, or Nitrile
Groups Initiated by the Acetoxypalladation of Alkynes. Angew. Chem.,
Int. Ed. 2002, 41, 4343. (b) Zhang, J.; Han, X.; Lu, X. Synthesis of
Cyclohexane-Fused Isocoumarins via Cationic Palladium(II)-Cata-
lyzed Cascade Cyclization Reaction of Alkyne-Tethered Carbonyl
Compounds Initiated by Intramolecular Oxypalladation of Ester-
Substituted Aryl Alkynes. J. Org. Chem. 2016, 81, 3423. (c) Chen, J.;
Han, X.; Lu, X. Atom-Economic Synthesis of Pentaleno[2,1-b]indoles
via Tandem Cyclization of Alkynones Initiated by Aminopalladation.
J. Org. Chem. 2017, 82, 1977. (d) Zhang, X.; Han, X.; Chen, J.; Lu, X.
Cationic Pd(II)-Catalyzed Arylative Cyclization of N-(2-Formylaryl)
alkynamides: An Efficient Route to 2-Quinolinones. Tetrahedron
2017, 73, 1541. (e) Chen, J.; Han, X.; Lu, X. Palladium(II)-Catalyzed
Asymmetric Tandem Cyclization of 2-Aminoaryl Alkynones: An
Approach to Chiral 1,2,3,4-Tetrahydro-β-carbolines. Org. Lett. 2018,
20, 7470.
(6) For examples of transmetalation initiated reactions of alkyne-
tethered ketones or aldehydes, see: (a) Song, J.; Shen, Q.; Xu, F.; Lu,
X. Cationic Pd(II)-Catalyzed Enantioselective Cyclization of
Aroylmethyl 2-Alkynoates Initiated by Carbopalladation of Alkynes
with Arylboronic Acids. Org. Lett. 2007, 9, 2947. (b) Han, X.; Lu, X.
Control of Chemoselectivity by Counteranions of Cationic Palladium
Complexes: A Convenient Enantioselective Synthesis of Dihydrocou-
marins. Org. Lett. 2010, 12, 108. (c) Wang, H.; Han, X.; Lu, X. Pd(II)-
Catalyzed Annulation of N-Benzyl-N-aroylmethyl-2-alkynamides with
Arylboronic Acids: An Efficient Synthesis of Highly Substituted α-
Alkylidene-β-hydroxy-γ-lactams. Tetrahedron 2010, 66, 9129.
(7) (a) Shen, K.; Han, X.; Lu, X. Cationic Pd(II)-Catalyzed
Reductive Cyclization of Alkyne-Tethered Ketones or Aldehydes
Using Ethanol as Hydrogen Source. Org. Lett. 2013, 15, 1732.
(b) Shen, K.; Han, X.; Xia, G.; Lu, X. Cationic Pd(II)-Catalyzed
Cyclization of N-Tosyl-aniline Tethered Alkynyl Ketones Initiated by
Hydropalladation of Alkynes: A Facile Way to 1,2-Dihydro or 1,2,3,4-
Tetrahydroquinoline Derivatives. Org. Chem. Front. 2015, 2, 145.
(c) Zhang, X.; Han, X.; Hu, Z.; Lu, X. Synthesis of Substituted
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