Geometrically biased homoconjugated ketones. Synthetic avenues to 1-acyl-2,4-cyclohexadienes (original) (raw)

1982, The Journal of Organic Chemistry

6-Methylenetricyclo[3.3,0.03~7]octan-2-one (6). A solution of 32 (361 mg, 2.65 mmol) in CH2C12 (4 mL) was added to a suspension of pyridinium chlorochromate (943 mg, 4.37 mmol) in CH2C12 (5 mL), and the mixture was stirred for 3 h at room temperature. The CH2C12 solution was separated, and the inorganic residue was rinsed with CH2C12 The combined CH2C12 solutions were concentrated, and the residue was chromatographed on neutral alumina. Fractions eluted with pentane gave a solid which was sublimed at 30 "C (5 mm) to afford 6: 125 mg (35% yield); mp 35.5-36 O C (in a sealed tube); UV (isooctane) A , 286 nm e 24.1); IR (KBr) 3075, 1770, 860 cm-'; NMR (CC14) 6 1.65 (s, 4 H), 2.22 (br s, 2 H), 2.72 (br s, 2 H), 4.62 (s, 2 H). Anal. Calcd for C9Hl00: C, 80.56; H, 7.51. Found C, 80.56; H, 7.52. Tricycl0[3.3.0.0~*~]octane-2,6-dione . A mixture of 6 (84 mg, 0.626 mmol), osmium tetraoxide (100 mg, 0.393 mmol), THF (2 mL), and water (2 mL) was stirred for 30 min at room temperature, and sodium metaperiodate (268 mg, 1.25 mmol) was added by portions over 40 min. After the mixture was stirred at room temperature for 14 h, the deposited inorganic solid was filtered, and this was rinsed with CH2C12. The CH2C12 extracts were combined with the original fitrate, and the mixture was made basic with 2 N aqueous NaOH (4 mL) and extracted with CH2C12 The extracts were washed with water and dried (MgS04). After removal of the solvent, the residue was chromatographed on neutral alumina. Early pentane-ether eluates recovered 6 (40 mg), and subsequent pentane-ether eluates afforded 7 ( I mg, 8% yield) which was recrystallized from hexane: mp 94-97 "C (in a sealed tube); UV (hexane) & 281 nm (c 28.7), 294 (sh) (t 25.7); IR (KBr) 1765 cm-'; NMR (CDCl3) 6 1.85 (s, 4 H), 2.55 (s,4 H). Anal. Calcd for C10H802: C, 74.99; H, 5.03. Found: C, 74.75; H, 5.15. Registry No.