Lewis Acid-Catalyzed Reaction of Allenes with Activated Ketone

Abstract

Allenes react with activated ketone to give the corresponding addition products in good yields and good stereoselectivities in the presence of Lewis acid Yb(OTf)₃ and acetic anhydride or acetyl chloride as a quencher under mild reaction conditions.

allenes - Lewis acid - activated ketone - acetic anhydride - acetyl chloride

References

For synthesis of allenes:

1a Brandsma L. Verkruijsse HD. Synthesis of Acetylenes, Allenes and Cumulenes   Elsevier; New York: 1981. 

1b For some recent reviews about the reactions of allenes, please see: Hashmi ASK. Angew. Chem. Int. Ed.  2000,  39:  3590 

1c Zimmer R. Dinesh C. Nandanan E. Khan FA. Chem. Rev.  2000,  100:  3067 

2 Shi M. Xu B. Tetrahedron Lett.  2003,  44:  3839 

3 Howell AR. Fan R. Truong A. Tetrahedron Lett.  1996,  37:  8651 

4 Chang H.-M. Cheng C.-H. Org. Lett.  2000,  2:  3439 

5 Kang S.-K. Kim Y.-M. Ha Y.-H. Yu C.-M. Yang H. Lim Y. Tetrahedron Lett.  2002,  43:  9105 

6

The X-ray crystal data of 3 has been deposited in CCDC with number 208298. Empirical Formula: C₁₄H₁₄O₅. Formula weight: 262.25. Crystal color, habit: colorless, prismatic. Crystal dimensions: 0.267 × 0.251 × 0.189 mm. Crystal system: monoclinic. Lattice type: primitive. Lattice parameters: a = 7.9550(8) Å, b = 9.5303 (9) Å, c = 17.5333 (17) Å, α = 90°, β = 98.933 (2)°, γ = 90°, V = 1313.1 (2) ų. Space group: P2 (1)/n; Z _value = 4; D _calc = 1.327 g/cm³; F ₀₀₀ = 552. Diffractometer: Rigaku AFC7R; Residuals: R1; wR2: 0.0413, 0.0722.

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Typical Procedure for the Reaction of Allenes with an Activated Ketone: Under argon atmosphere, allene 1a (58 mg, 0.5 mmol), Yb(OTf)₃ (0.0025 mmol) and mesoxalate 2 (139 mg, 0.8 mmol), acetyl chloride (1.5 mmol) was dissolved in 1.5 mL of CH₂Cl₂, the reaction mixture was stirred for 18 h at r.t., then the reaction was quenched with aq. NaHCO₃ solution. The organic layer was washed with H₂O and dried over MgSO₄. The solvent was removed under reduced pressure and the residue was purified by passing through a silica gel column chromatography (SiO₂, hexane/EtOAc = 10/1 as an eluent) to afford adducts 5a (156 mg) as a colorless oil, yield 85%. IR (neat): 2893, 1754, 1446, 1241, 1055, 912 cm^-1. ¹H NMR (300 MHz, CDCl₃, TMS): δ = 1.32 (t, J = 7.2 Hz, 6 H), 2.28 (s, 3 H), 4.30 (q, J = 7.2 Hz, 4 H), 4.43 (s, 2 H), 7.10 (s, 1 H), 7.34-7.48 (m, 5 H, Ar). ¹³C NMR (75 MHz, CDCl₃): δ = 13.70, 20.52, 39.26, 62.55, 82.33, 128.41, 128.55, 128.69, 130.38, 134.40, 136.10, 165.07, 169.22. MS (EI): m/z = 368, 333, 308, 273, 235, 199, 143, 115. HRMS (EI): Calcd for C₁₈H₂₁ClO₆ (M⁺): 368.1027. Found: 368.1026.

8 Ghosh S. Pardo SN. Salomon RG. J. Org. Chem.  1982,  47:  4692