Bis(p-allylhimachalene)dichlorodipalladium

Larbi El Firdoussi and Abdellah Karim

Laboratoire de Chimie de Coordination Faculté des Sciences Semlalia, BP 2390 Marrakech Maroc. Fax: 212 44 43 74 08.
E-mail: [email protected]

Received: 11 December 2000 / Accepted: 15 December 2000 / Published: 25 March 2001

The title organometallic compound, potentially important synthetic intermediate, was prepared regio- and stereospecifically from b-himachalene ((4aR)-3,5,5,9-Tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), essentiel component of cedrus atlantica oil [1].

A red solution of Na₂PdCl₄, prepared in situ by mixing PdCl₂ (100 mg, 0.56 mmol), LiCl (71.2 mg, 1.45 mmol) and sodium acetate (238 mg, 2.9 mmol) in glacial acetic acid (10 mL), was stirred at 85°C for 30 min. The mixture was then cooled to 60°C, after which CuCl₂ (227 mg, 1.69 mmol) and b-himachalene 1 (346 mg, 1.69 mmol) were added. The resulting mixture was further stirred for 12 h. The resulting mixture was filtered and extracted with ether (3x20 mL). The combined organic layers was neutralized with a saturated solution of NaHCO₃, dried over anhydrous MgSO₄ and concentrated to afford an orange oil. Flash chromatography of the crude product over silica gel using hexane-ethyl acetate (95:5) furnished analytically pur complex 2 (54% yield) as a yellow solid [2].

M.p. 124-125 °C (decomposition).

¹H NMR (400 MHz, CD₂Cl₂): 5.46 (1H, m, =CH), 4.32 (1H, t, J=3Hz, HC5), 3.37 (1H, d, J=3.3Hz, HC1), 1.7 (3H, s, CH₃), 1.15 (3H, s, CH₃), 1.01 (3H, s, CH₃), 0.72 (3H, s, CH₃).

¹³C NMR (100 MHz, CD₂Cl₂) : 132.0 (C3), 120.1 (C2), 119.2 (C6), 86.5 (C7), 73.3 (C5), 45.9 (C1), 43.5 (CH₂), 37.43 (C11), 35.5 (CH₂), 31.8 (CH₂), 28.7 (CH₃), 23.6 (CH₃), 23.1 (CH₃), 22.5 (CH₃), 18.8 (CH₂).

Anal.Calc. for (C₁₅H₂₃PdCl)₂ : C 52.21, H 6.66, Cl 10.14, Pd 30.84. Found: C 52.22, H 6.70, Cl 10.10, Pd 70.72.

References

1.	Joseph, T.C.; Dev, S. Tetrahedron1968, 24, 3841.
2.	Chiaroni, A.; Riche, C.; El Firdoussi, L.; Benharref, A.; Karim, A. Acta Cryst. 1993, C49, 365-368.

Sample availability: available from the authors and MDPI.

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