Ru-Catalyzed Enantioselective Dipolar Cycloadditions of Ethyl Diazopyruvate

Abstract

The decomposition of ethyl diazopyruvate (1) with [RuCl₂(pybox)] catalysts in the presence of enol ethers affords ­dihydrofurans derived from formal 1,3-cycloaddition. Enantio­selectivities of up to 74% have been achieved.

asymmetric catalysis - cycloaddition - diazo compounds - carbenes - ruthenium

References

<A NAME="RG31304ST-1">1</A> Pfaltz A. Cyclopropanation and C-H Insertion with Cu, In Comprehensice Asymmetric Catalysis   Jacobsen EN. Pfaltz A. Yamamoto H. Springer; Berlin: 1999.  Chap. 16.1. p.516 

<A NAME="RG31304ST-2A">2a</A> Doyle MP. McKervey MA. Ye T. Modern Catalytic Methods for Organic Synthesis with Diazo Compounds: From Cyclopropanes to Ylides   Wiley; New York: 1998.  Chap. 2.

<A NAME="RG31304ST-2B">2b</A> Doyle MP. Forbes DC. Chem. Rev.  1998,  98:  911 

<A NAME="RG31304ST-2C">2c</A> Davies HML. Aldrichimica Acta  1997,  30:  107 

<A NAME="RG31304ST-2D">2d</A> Davies HLM. Eur. J. Org. Chem.  1999,  2459 

<A NAME="RG31304ST-3">3</A> Alonso ME. Morales A. Chitty AW. J. Org. Chem.  1982,  47:  3747 

<A NAME="RG31304ST-4A">4a</A> Alonso ME. Jano P. Hernandez MI. Greenberg RS. Wenkert E. J. Org. Chem.  1983,  48:  3047 

<A NAME="RG31304ST-4B">4b</A> Wenkert E. Alonso ME. Buckwalter BL. Sanchez EL. J. Am. Chem. Soc.  1983,  105:  2021 

<A NAME="RG31304ST-4C">4c</A> Alonso ME. Hernandez MI. Gomez M. Jano P. Pekerar S. Tetrahedron  1985,  41:  2347 

<A NAME="RG31304ST-5A">5a</A> Pirrung MC. Zhang J. Lackey K. Sternbach DD. Brown F. J. Org. Chem.  1995,  60:  2112 

<A NAME="RG31304ST-5B">5b</A> Pirrung MC. Zhang J. McPhail AT. J. Org. Chem.  1991,  56:  6269 

<A NAME="RG31304ST-5C">5c</A> Pirrung MC. Lee YR. Tetrahedron Lett.  1994,  35:  6231 

<A NAME="RG31304ST-5D">5d</A> Pirrung MC. Lee YR. J. Am. Chem. Soc.  1995,  117:  4814 

<A NAME="RG31304ST-5E">5e</A> Pirrung MC. Blume F. J. Org. Chem.  1999,  64:  3642 

<A NAME="RG31304ST-6A">6a</A> Müller P. Acc. Chem. Res.  2004,  37:  243 

<A NAME="RG31304ST-6B">6b</A> Lee YR. Cho BS. Bull. Korean Chem. Soc.  2002,  23:  779 

<A NAME="RG31304ST-6C">6c</A> Batsila C. Kostakis G. Hadjarapoglou LP. Tetrahedron Lett.  2002,  43:  5997 

<A NAME="RG31304ST-6D">6d</A> Asouti A. Hadjiarapoglou LP. Tetrahedron Lett.  1998,  39:  9073 

<A NAME="RG31304ST-7">7</A> Pirrung MC. Zhang J. Morehead AT. Tetrahedron Lett.  1994,  35:  6229 

<A NAME="RG31304ST-8A">8a</A> Müller P. Allenbach YF. Bernardinelli G. Helv. Chim. Acta  2003,  86:  3164 

<A NAME="RG31304ST-8B">8b</A> Gogonas EP. Hadjiarapoglou LP. Tetrahedron Lett.  2000,  41:  9299 

<A NAME="RG31304ST-9A">9a</A> Pirrung MC. Zhang J. Tetrahedron Lett.  1992,  33:  5987 

<A NAME="RG31304ST-9B">9b</A> Ishitani H. Achiwa K. Heterocycles  1997,  46:  153 

<A NAME="RG31304ST-10">10</A> Müller P. Allenbach YF. Ferri M. Bernardinelli G. ARKIVOC  2003,  VII:  80 

<A NAME="RG31304ST-11">11</A> Davies HML. Panaro SA. Tetrahedron  2000,  56:  4871 

<A NAME="RG31304ST-12">12</A> Davies HML. Ahmed G. Calvo RL. Churchill MR. Churchill DG. J. Org. Chem.  1998,  63:  2641 

<A NAME="RG31304ST-13">13</A> Maas G. Chem. Soc. Rev.  2004,  33:  183 

<A NAME="RG31304ST-14">14</A> Bachmann S. Mezzetti A. Helv. Chim. Acta  2001,  84:  3963 

<A NAME="RG31304ST-15">15</A> Nishiyama H. Itoh Y. Sugawara Y. Matsumoto H. Aoki K. Itoh K. Bull. Chem. Soc. Jpn.  1995,  68:  1247 

<A NAME="RG31304ST-16">16</A>

Müller, P.; Chappellet, S. Helv. Chim. Acta, to be published.

<A NAME="RG31304ST-17A">17a</A> Doyle MP. Davies SB. Hu W. Org. Lett.  2000,  2:  1145 

<A NAME="RG31304ST-17B">17b</A> Doyle MP. Hu W. ARKIVOC  2003,  VII:  15 

<A NAME="RG31304ST-18">18</A>

Sample Run. Cycloaddition of 1 to 2 in PhCH ₃ . Ethyl 4,5-dihydro-3a H -furo[2,3- b ]furan-2-carboxylate ( 3): (S,S)-2,6-Bis(4-isopropyl-2-oxazolin-2-yl)pyridine (86 mg, 0.294 mmol) was added to a solution of [RuCl₂(p-cymene)]₂ (58 mg, 0.095 mmol) in CH₂Cl₂. The dark red mixture was stirred at r.t. for 1 h under argon atmosphere. The solvent was removed under reduced pressure. Dihydrofuran (1.4 mL) and a solution of ethyl diazopyruvate (100 mg, 0.950 mmol) in PhCH₃ (3.0 mL) was added. The resulting suspension was stirred until complete consumption of starting material (thin layer chromatography). The mixture was concentrated, and the residue was purified by column chromatography on silica gel using EtOAc-pentane (60:40) as eluent afforded a pale yellow oil in 68% yield (104 mg, 0.620 mmol); [α]_D ²⁰ 17 (c 1.12, CDCl₃) for 74% ee. IR: 2983, 2281, 1737, 1633 cm^-1. ¹H NMR (300 MHz, CDCl₃): d = 6.25 (d, J = 8.0 Hz, 1 H), 5.84 (d, J = 3.5 Hz 1 H), 4.32 (q, J = 9.3 Hz, 2 H), 4.11 (m, 1 H), 3.78 (m, 2 H), 2.13 (m, 1 H), 1.96 (m, 3 H). ¹³C NMR (75 MHz, CDCl₃): δ = 159.7 (s), 148.8 (s), 111.7 (d), 110.5 (d), 67.1 (t), 61.4 (t), 47.6 (d), 31.2 (t), 14.2 (q). HRMS: m/z calcd for C₉H₁₂O₄ ⁺: 184.0738; found: 184.0718. Enantiomer separation: Supelco β-dex column (isothermal 140 °C) τ₁: 43.9 min (87%), τ₂: 45.7 min (13%).

<A NAME="RG31304ST-19A">19a</A> Nishiyama H. Kondo M. Nakamura T. Itoh K. Organometallics  1991,  10:  500 

<A NAME="RG31304ST-19B">19b</A> Müller P. Boléa C. Helv. Chim. Acta  2001,  84:  1093 

<A NAME="RG31304ST-19C">19c</A> Davies IW. Gerena L. Lu N. Larsen RD. Reider PJ. J. Org. Chem.  1996,  61:  9629 

<A NAME="RG31304ST-19D">19d</A> Iwasa S. Tshushima S. Shimada T. Nishiyama H. Tetrahedron  2002,  58:  227