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DOI: 10.1055/s-2003-36218
Extended Scope of Dirhodium(II)-Catalysed Enantioselective Intramolecular 1,3-Dipolar Cycloadditions of Carbonyl Ylides with Alkene and Alkyne Dipolarophiles
Publication History
Publication Date:
18 December 2002 (online)
Abstract
Catalytic enantioselective tandem carbonyl ylide formation-intramolecular 1,3-dipolar cycloaddition reactions of 2-diazo-3,6-diketoesters show promising scope in terms of asymmetric induction as the tethered alkene/alkyne dipolarophile component is varied.
Key words
asymmetric catalysis - rhodium - ylides - cycloadditions - diazo compounds
- 1
Cycloaddition
Reactions in Organic Synthesis
Kobayashi S.Jørgensen KA. Wiley-VCH; Weinheim: 2002. - 2
Synthetic
Applications of 1,3-Dipolar Cycloaddition Chemistry Toward Heterocycles
and Natural Products
Padwa A.Pearson WH. John Wiley and Sons; New York: 2002. -
3a
Padwa A.Weingarten MD. Chem. Rev. 1996, 96: 223 -
3b
Doyle MP.McKervey MA.Ye T. Modern Catalytic Methods for Organic Synthesis with Diazo Compounds John Wiley and Sons; New York: 1998. Chap. 7. -
3c
Clark JS. Nitrogen, Oxygen and Sulfur Ylide Chemistry Oxford University Press; Oxford: 2002. -
3d
Mehta G.Muthusamy S. Tetrahedron 2002, 58: 9477 -
3e For a recent application,
see:
Hodgson DM.Avery TD.Donohue AC. Org. Lett. 2002, 4: 1809 - 4
Hodgson DM.Stupple PA.Johnstone C. Tetrahedron Lett. 1997, 38: 6471 -
5a
Hodgson DM.Stupple PA.Johnstone C. Chem. Commun. 1999, 2185 -
5b
Hodgson DM.Stupple PA.Pierard FYTM.Labande AH.Johnstone C. Chem.-Eur. J. 2001, 7: 4465 -
6a
Kitagaki S.Masahiro A.Kataoka O.Matsuno K.Umeda C.Watanabe N.Hashimoto S. J. Am. Chem. Soc. 1999, 121: 1417 -
6b
Kitagaki S.Yasugahira M.Anada M.Nakajima M.Hashimoto S. Tetrahedron Lett. 2000, 41: 5931 -
7a
Hodgson DM.Pierard FYTM.Stupple PA. Chem. Soc. Rev. 2001, 30: 50 -
7b
Hodgson DM.Stupple PA.Forbes DC. In Rodd’s Chemistry of Carbon Compounds, Topical Volume, Asymmetric CatalysisSainsbury M. Elsevier; Oxford: 2001. p.65 -
7c
Kitagaki S.Hashimoto S. J. Synth. Org. Chem. Jpn. 2001, 59: 1157 -
8a
Hodgson DM.Glen R.Redgrave AJ. Tetrahedron Lett. 2002, 43: 3927 -
8b
Hodgson DM.Glen R.Grant GH.Redgrave AJ. J. Org. Chem. 2002, in press - 14
Padwa A.Hornbuckle SF.Fryxell GE.Zhang ZJ. J. Org. Chem. 1992, 57: 5747 - 15 For a recent example, see:
Graening T.Friedrichsen W.Lex J.Schmalz H.-G. Angew. Chem. Int. Ed. 2002, 41: 1524 - 17
Davies HML. Eur. J. Org. Chem. 1999, 2459
References
A significant erosion in ee (and yield) has been observed for one (oxidopyrylium) substrate as the dipolarophile was even varied from DMAD (74% ee) to the corresponding diethyl ester (46% ee); 25% ee was observed with the di-tert-butyl ester. [6b]
10Results in CH2Cl2 for all the substrates examined in the current paper are not given here; as previously found with 1, [5] the ees were uniformly lower than in hexane.
11Hashimoto’s optimized catalyst-solvent combination [6] was not studied, since it had previously been shown with 1 to generate only racemic cycloadduct 3. [5]
12Ees were determined directly on the cycloadducts by GC analysis and comparison with racemic samples prepared using Rh2(OAc)4 (chiral gas chromatography was carried out using a CE Instruments Trace GC (Thermoquest) machine with a CP Chirasil Dex-CD column).
13NOE experiments support the relative stereochemistry of the cycloadducts shown in Scheme [3] . The absolute configurations of the predominant cycloadduct enantiomers are tentatively assigned as those shown, by analogy with cycloadduct (+)-3 of known absolute configuration. [5] Selected specific rotation values (c 1.0, CHCl3): for (+)-14, using 5 at 0 °C: [α]D 24 +38.0; for (-)-15, using 5 at -15 °C: [α]D 25 -29.7; for (-)-16, using 5 at 0 °C: [α]D 25 -8.2; for (+)-17, using 5 at 0 °C: [α]D 24 +23.2.
16
Typical Procedure
for Cycloadduct (+)-18: To a stirred, degassed
solution tert-butyl 2-diazo-3,6-dioxoundec-10-ynoate
(100 mg, 0.34 mmol) in hexane (5 mL) at 25 °C
was added Rh2[(R)-DDBNP]4 (10
mg, 0.0034 mmol). After 30 min, the reaction mixture was concentrated
in vacuo. The residue was purified by flash chromatography (SiO2,
light petroleum-Et2O 8:2; Rf = 0.11)
to afford a white solid (70 mg, 77%). IR(neat): νmax = 2974,
2923, 1743, 1720, 1368, 1306, 1158, 1057 cm-1. 1H
NMR (400 MHz, CDCl3): δ = 5.86 (t,
1 H, J
4
= 2.0
Hz), 2.89-2.80 (m, 1 H), 2.52-2.24 (m, 4 H), 2.16-2.00
(m, 3 H), 1.97-1.90 (m, 1 H), 1.77-1.69 (m, 1
H), 1.50 (s, 9 H). 13C NMR (100 MHz;
CDCl3): δ = 198.8, 165.1, 157.4, 119.2,
100.2, 96.5, 82.8, 33.0, 32.8, 29.6, 28.0, 26.2, 22.6. MS: m/z (%) [CI + (NH3)] = 282(46) [M + NH4
+], 265(10) [M + H+),
226(100) {M - [CH2C(CH3)2] + NH4
+}. HRMS
(ES, [M + H]+) calcd
265.1440, measured 265.1449. GC analysis for ee determination: (CP
Chirasil Dex-CD,
80° C/1 min/5° Cmin-
1/170° C/100
min, 0.5 mLmin-
1, 2 mgmL-1), t
Rmn = 27.2
min; t
Rmj = 27.9
min.
Selected specific rotation values (c 1.0, CHCl3): for (+)-19, using 5 at -15 °C: [α]D 25 +305.4; (+)-20, using 5 at 0 °C: [α]D 25 +283.9; (+)-21, using 5 at 0 °C: [α]D 24 +231.2.