Bis(p-allylhimachalene)dichlorodipalladium

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.