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DOI: 10.1055/s-0029-1217368
Ni-Catalyzed Carbocyclization of 1,6-Enynes Mediated by Dialkylzinc Reagents: Me2Zn or Et2Zn Makes a Difference
Publikationsverlauf
Publikationsdatum:
12. Juni 2009 (online)
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Abstract
Unactivated 1,6-enynes were firstly found to undergo different cyclization process under the catalysis of Ni0 species in situ generated from NiII complexes and dialkylzinc reagents. When stoichiometric Me2Zn was used as the reducing agent, only the dimerization products {[2+2+2+2] or [2+2+2]} were obtained. On the other hand, reductive cyclization products were obtained solely when 0.6 equivalents of Et2Zn were employed as the reductant under otherwise the same reaction conditions. In the former case, up to 1:7 selectivity in favor of the [2+2+2] products was also achieved with NiCl2(PPh3)2/Me2Zn.
Key words
organozinc reagents - enynes - cyclizations - nickel
- Supporting Information for this article is available online:
- Supporting Information
- Reviews:
-
1a
Montgomery J. Angew. Chem. Int. Ed. 2004, 43: 3890 -
1b
Moslin RM.Miller-Moslin K.Jamison TF. Chem. Commun. 2007, 4441 -
1c
Michelet V.Toullec PY.Genêt J.-P. Angew. Chem. Int. Ed. 2008, 47: 4268 -
1d A special issue on nickel
catalysis:
Jamison TF. Tetrahedron 2006, 62: 7499 -
1e
Wang C.Xi Z. Chem. Soc. Rev. 2007, 36: 1395 - For recent examples, see:
-
2a
Maeda K.Saito S. Tetrahedron Lett. 2007, 48: 3173 -
2b
Komagawa S.Saito S. Angew. Chem. Int. Ed. 2006, 45: 2446 -
2c
Tekavec TN.Louie J. J. Org. Chem. 2008, 73: 2641 -
2d
Tekavec TN.Louie J. Tetrahedron 2008, 64: 6870 -
2e
Duong HA.Louie J. Tetrahedron 2006, 62: 7552 -
2f
Tekavec TN.Zuo G.Simon K.Louie J. J. Org. Chem. 2006, 71: 5834 -
2g
Duong HA.Louie J. J. Organomet. Chem. 2005, 690: 5098 -
2h
Tekevac TN.Louie J. Org. Lett. 2005, 7: 4037 -
2i
McCormick MM.Duong HA.Zuo G.Louie J. J. Am. Chem. Soc. 2005, 127: 5030 -
2j
Duong HA.Cross MJ.Louie J. J. Am. Chem. Soc. 2004, 126: 11438 -
2k
Ikeda S.Daimon N.Sanuki R.Odashima K. Chem. Eur. J. 2006, 12: 1797 -
2l
Ikeda S.Obara H.Tsuchida E.Shirai N.Odashima K. Organometallics 2008, 27: 1645 -
2m
Ashida S.Murakami M. Bull. Chem. Soc. Jpn. 2008, 81: 885 -
3a
Herath A.Thompson BB.Montgomery J. J. Am. Chem. Soc. 2007, 129: 8712 -
3b
Herath A.Montgomery J. J. Am. Chem. Soc. 2006, 128: 14030 -
3c
Jayanth TT.Cheng C.-H. Angew. Chem. Int. Ed. 2007, 46: 5921 -
3d
Ogoshi S.Ikeda H.Kurosawa H. Angew. Chem. Int. Ed. 2007, 46: 4930 -
3e
Patel SJ.Jamison TF. Angew. Chem. Int. Ed. 2003, 42: 1364 - For recent examples, see:
-
5a
Kimura M.Ezoe A.Mori M.Iwata K.Tamura Y. J. Am. Chem. Soc. 2005, 127: 201 -
5b
Kimura M.Ezoe A.Mori M.Iwata K.Tamura Y. J. Am. Chem. Soc. 2006, 128: 8559 -
5c
Yang Y.Zhu S.-F.Duan H.-F.Zhou C.-Y.Wang L.-X.Zhou Q.-L.
J. Am. Chem. Soc. 2007, 129: 2248 -
5d For a review, see:
Ikeda S. Angew. Chem. Int. Ed. 2003, 42: 5120 -
6a
Joensuu PM.Murray GJ.Fordyce EAF.Luebbers T.Lam HW. J. Am. Chem. Soc. 2008, 130: 7328 -
6b
Villanueva MI.Rupnicki L.Lam HW. Tetrahedron 2008, 64: 7896 -
6c
Lam HW.Joensuu PM.Murray GJ.Fordyce EAF.Prieto O.Luebbers T. Org. Lett. 2006, 8: 3729 -
6d
Lam HW.Murray GJ.Firth JD. Org. Lett. 2005, 7: 5743 - 7
Chen M.Weng Y.Guo M.Zhang H.Lei A. Angew. Chem. Int. Ed. 2008, 47: 2279 - 8
Zhao Z.Ding Y.Zhao G. J. Org. Chem. 1998, 63: 9285 - For a example of Rh-catalyzed homodimerization of 1,6-enynes, see:
-
10a
Evans PA.Robinson JE.Baum EW.Fazal AN. J. Am. Chem. Soc. 2002, 124: 8782 - For similar reactions of dieneynes catalyzed by Rh, see:
-
10b
DeBoef B.Gilbertson SR. J. Am. Chem. Soc. 2002, 124: 8784 -
10c
DeBoef B.Counts WR.Gilbertson SR. J. Org. Chem. 2007, 72: 799 - For examples of nickel metallocyclopentadienes in the homodimerization of 1,3-perfluoroalkylenynes, see:
-
10d
Saito S.Tanaka T.Koizumi T.Tsuboya N.Itagaki H.Kawasaki T.Endo S.Yamamoto Y. J. Am. Chem. Soc. 2000, 122: 1810 -
10e
Saito S.Kawasaki T.Tsuboya N.Yamamoto Y. J. Org. Chem. 2001, 66: 796 - 11
Wender PA.Christy JP. J. Am. Chem. Soc. 2007, 129: 13402 - The combined use of 6 mol% of Cy3P and 5 mol% of Ni(acac)2 only led to a ratio of 1.5:1 favoring the [2+2+2] product 3a. Attempts to interject the reaction intermediate with a third alkyne (3 equiv) resulted in a complex mixture (when ethyl 3-phenylpropiolate was used) or the recovery of most of the starting 1,6-enyne 1a (when phenylacetylene or 1-hexyne were used), however, similar strategy was successful with Rh-catalyzed reactions of unactivated 1,6-enynes:
-
12a
Baik M.-H.Baum EW.Burland MC.Evans PA. J. Am. Chem. Soc. 2005, 127: 1602 -
12b
Evans PA.Lai KW.Sawyer JR. J. Am. Chem. Soc. 2005, 127: 12466 -
12c
Evans PA.Sawyer JR.Lai KW.Huffman JC. Chem. Commun. 2005, 63 -
12d
Evans PA.Baum EW.Fazal AN.Pink M. Chem. Commun. 2005, 3971 - 16 For examples of similar phenomena:
Tamao K.Kobayashi K.Ito Y. J. Am. Chem. Soc. 1988, 110: 1286 ; and ref. 7 - For corresponding studies, see:
-
18a
Didiuk MT.Morken JP.Hoveyda AH. J. Am. Chem. Soc. 1995, 117: 7273 -
18b
Morken JP.Didiuk MT.Hoveyda AH. Tetrahedron Lett. 1996, 37: 3613 -
18c
Nomura N.RajanBabu TV. Tetrahedron Lett. 1997, 38: 1713 -
18d
Didiuk MT.Morken JP.Hoveyda AH. Tetrahedron 1998, 54: 1117 -
18e
Taniguchi T.Ogasawara K. Angew. Chem. Int. Ed. 1998, 37: 1136 -
18f
Lautens M.Ma S.Rovis T. J. Am. Chem. Soc. 1995, 117: 532 ; and ref. 5a - For selected examples for the reductive cyclization of unactivated 1,6-enynes using Rh and Ti catalysts, see:
-
20a
Jang H.-Y.Hughes FW.Gong H.Zhang J.Brodbelt JS.Krische MJ. J. Am. Chem. Soc. 2005, 127: 6174 -
20b
Jang H.-Y.Krische MJ. J. Am. Chem. Soc. 2004, 126: 7875 -
20c
Montchamp J.-L.Negishi E. J. Am. Chem. Soc. 1998, 120: 5345
References and Notes
Dialkylzinc reagents, zinc powder, triethylsilane, triethylboranes, and DIBAL-H have been used as the reducing agent in this type of transformation.
9For examples of Ni-catalyzed reductive cyclization pro-cesses with the methyl shift involving Me2Zn, see ref. 5a and references cited therein.
13CCDC 690610(3a) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data-request/cif. See the Supporting Information for a figure of its X-ray structure.
14The [2+2+2+2] process has been found to be favored at a large loading amount of Ni catalyst for the dimerization of terminal 1,6-diynes, see ref. 10.
15When 50 mol% or 20 mol% of Me2Zn were used, the reaction failed to proceed.
17CCDC 690609(2h) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data-request/cif. See the Supporting Information for a figure of its X-ray structure.
19In ref. 7, the authors also proposed that oligomerization may be the possible reason for the decreased yield with 1j.
21The addition of 5 mol% of Ph3P, PCy3 or (R)-BINAP did not improve the product selectivity significantly.
22
Typical Procedure
for the Dimerization of 1 with Ni
II
/Me
2
Zn Combination
Under an atmosphere
of argon, 3.2 mg (0.012 mmol) of Ni(acac)2 were added
to a Schlenk tube, and the system was purged with argon three times.
Then enyne 1a (86 mg, 0.3 mmol) in 3.0
mL of freshly distilled THF was added via a syringe followed by
the addition of Me2Zn 0.3 mmol (1.2 M in toluene) in
one portion [in the case of NiCl2(PCy3),
Me2Zn was added at reflux]. The reaction mixture
was stirred for 1 h at r.t. before being quenched with sat. aq NH4Cl
soln. Then, the mixture was extracted with CH2Cl2 (3 × 3
mL), dried with anhyd Na2SO4. After removal
of the solvent in vacuum, the residue was purified by column chromatography
(silica gel, PE-Et2O = 4:1)
to provide the desired products 2a and 3a.
(5
E
,10
E
)-Tetramethyl-5,10-diphenyl-3a,4,8a,9-tetrahydropyrene-2,2,7,7(1
H
,3
H
,6
H
,8
H
)-tetracarboxy-late (2a)
Colorless crystal; mp 193-194 ˚C
(hexane-Et2O). ¹H NMR (300
MHz, CDCl3): δ = 7.36-7.17
(m, 10 H), 3.67 (s, 6 H), 3.63 (s, 6 H), 3.05-2.70 (m,
10 H), 2.24 (d, J = 10.6
Hz, 2 H), 1.95-1.89 (dd, J = 13.1,
6.8 Hz, 2 H) ppm. ¹³C NMR (75 MHz,
CDCl3): δ = 172.0, 171.7, 145.2, 144.2,
136.1, 128.3, 127.7, 126.3, 59.4, 52.60, 52.59, 46.2, 43.9, 43.0,
40.4 ppm. IR (KBr): 2952, 1734, 1434, 1250, 1205, 1070, 703 cm-¹. MS
(EI): m/z = 572 [M+],
167(base). HRMS (EI): m/z calcd for
C34H36O8: 572.2410; found: 572.2413.
Dimethyl 6-[2,2-Bis(methoxycarbonyl)pent-4-enyl]-5,7-diphenyl-3a,4-dihydro-1
H
-indene-2,2(3
H
)-dicarboxy-late
(3a)
Colorless crystal;¹³ mp
87-89 ˚C (hexane-Et2O). ¹H
NMR (300 MHz, CDCl3): δ = 7.39-7.18
(m, 10 H), 4.86-4.74 (m, 1 H), 4.58-4.68 (m, 2
H), 3.77 (s, 3 H), 3.64 (s, 3 H), 3.46 (s, 3 H), 3.36 (s, 3 H),
3.32-3.22 (m, 1 H), 2.97-2.57 (m, 5 H), 2.28 (d, J = 6.9 Hz,
2 H), 2.14 (t, J = 17.4
Hz, 1 H), 2.02-1.95 (dd, J = 13.2,
8.8 Hz, 2 H) ppm. ¹³C NMR (75 MHz, CDCl3): δ = 172.2,
171.9, 171.1, 142.1, 141.4, 139.2, 133.7, 133.1, 130.1, 129.8, 129.6,
128.4, 128.0, 127.8, 127.0, 126.6, 117.7, 60.2, 59.0, 52.9, 52.7,
52.0, 39.6, 39.1, 38.5, 38.4, 37.8, 30.5 ppm. IR (KBr): 2953, 1732,
1491, 1435, 1380, 763, 735, 703 cm-¹.
MS (EI): m/z = 572 [M+], 279(base).
HRMS (EI): m/z calcd for C34H36O8Na+: 595.2316 ± 0.002;
found: 595.2302.