Chlorohydridobis trimethylphosphine platinum II

Into a SO-mL Schlenk flask is weighed 0.2S g of the recrystallized cis-dichlorobis(trimethylphosphine)platinum(II). Under a nitrogen atmosphere, the solid is suspended in 10 mL of methanol (refluxed under nitrogen and distilled from magnesium). To the suspension is added 3 mL of diethylamine (distilled and stored under nitrogen), and the suspension is stirred until the solid dissolves. Then 1 equiv (0.022 g) of sodium tetrahydroborate(l —) is added and stirring continued for about S min until gas evolution ceases. The 

McNally, V. S. Leong, and N. J. Cooper, Experimental Organometallic Chemistry, ACS Symposium Series 357, American Chemical Society, Washington, DC, 1987, p. 6. 

6-Tetrahydro-2,3,5,6-tetramethyl-y-pyrone (1). A 12-L, three-necked, round-bottomed flask fitted with an efficient mechanical stirrer and a gas inlet is flushed with dinitrogen. Under a dinitrogen flush, 2360 mL of methanol and 380 g (6.77 mol) of KOH are added to the flask. The solution is then cooled to 0°C in an ice bath and 2000 mL (18.9 mol) 3-pentanone (Aldrich) is added under a dinitrogen flush. The solution is maintained at 0°C, and 4245 mL (75.5 mol) of acetaldehyde (Fluka, puriss) is added dropwise with stirring over a period of 36 h. During the addition of acetaldehyde, the color of the reaction mixture changes to a deep red, then to a dark brownish red color. After acetaldehyde addition is complete, the reaction solution is stirred an additional 12h at 0°C. 

5-Tetramethylcyclopent-2-enone (2). A 12-L, three-necked, round-bottomed reaction flask is cooled in an ice bath. It is charged with 6500 mL of 95-97% HCOOH (Aldrich) and 2250 mL of concentrated H2SO4 (exothermic), and the solution is allowed to cool to room temperature. The 2,3,5,6-tetrahydro-2,3,5,6-tetramethyl-y-pyrone, 1580 g (1, 10.1 mol), is then added with rapid stirring to the acid solution at a fast trickle. After addition is 

Burger, A. Delay, and F. Mazenod, Helv. Chim. Acta, 57, 2106 (1974). 

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