PERHYDROINDAN DERIVATIVES. X 961 lization from methanol afforded the pure diester l b as colorless prisms: mp 86-87'; ir (CCL), 1740 (ester C=O) and 1660 cm-1 (weak, C=C); uv maxima, 266 mp (e 274), 270 (shoulder, 223), and 274.5 (200); nmr (CCh), Q 6.7-7.2 (3 H multiplet, aryl CH), 5.1-5.9 (2 H multiplet, vinyl CH), 4.0-4.3 (1 H multiplet, benzylic CH), 3.79 (1 H singlet, benzylic CH), 3.63 (3 H singlet, OCHI), 3.53 (3 H singlet, OCHa), 2.28 (3 H singlet, aryl CHs), and 1.6-2.9 (4 H multiplet, aliphatic CH); mass spectrum, molecular ion peak a t m/e 300, abundant fragment peaks a t m/e 181. 180, 166, and 165. Anal. Calcd for C18H2004: C, 71.98; H, 6.71. Found: C, 71.86; H , 6.81.A solution of 172 mg (0.51 mmol) of the diester l b and the sodium methoxide from 75 mg (3.3 mg-atom) of sodium in 3.0 ml of methanol-dl was refluxed for 3 days and poured into a mixture of deuterium oxide and acetic acid-dl. The resulting mixture was concentrated under reduced pressure and an ether solution of the residue was washed successively with aqueous NaHCOa and aqueous NaCl and then dried and concentrated to leave 159 mg (93%) of the crude partially deuterated diester lb, mp 76-82'. liecrystallization from methanol afforded 94 mg of the ester lb, mp 84-85', which contained 16% do species and 84% dl species. The nmr spectrum of this material corresponded to the spectrum previously described except that the singlet at 6 3.79 (benzylic CH) was markedly reduced in intensity.A mixture of 1.064 g (3.08 mmol) of the etherate of the diacid l a and 632 mg of a 30yl, palladium-on-carbon catalyst was heated to 235' under a slow stream of nitrogen for 2.25 hr. The resulting mixture was extmcted with boiling chloroform and the chloroform extract was filtered and concentrated. Recrystallization of the residual white solid from ethanol separated 243 mg (50.5%) of I-methylfluorene (18) as white prisms, mp 83-84.5'; after sublimation at 80" (3 mm), the material melted at 85-87' (lit. mp 85',18s 86' l B b ) . l B This material was identified with a sub-(18) (a) L. A. Pinck and G. E. Hilbert, J . Amer. Chem. Soc., 68, 751 (1946); (b) W. C. Lothrup and P . A. Goodwin, ibid., 65,363 (1943). (19) The other possible product would have been 4-methylfluorene (21) which is reported to melt at. 71.5-72.5' [M. Orchin and E. 0. Woolfolk. ibid.. 67, 122 (1945); and 70.4-71.2° [L.Both of the double-bond isomers of 1,2-dicarbomethoxy-6-methoxyindene (4 and 17) and l,%dicarbomethoxy-I n each case the less highly substituted double isomer 4 or 20 is the However, derivatives of each of these indenes react with 1,Sbutadiene to give the Diels-Alder indene (19 and 20) have been synthesized. more stable. adduct, derived from the more highly substituted doublebond isomer.
