literature data for the exo and endo isomers. Discuss which isomer
you obtained and how you know from your
analysis. Please analyze the NMR and compare it to the
literature value and don't just say that the endo is
favored.
- Compare The Nmr Spectrum For The Reaction Below To The Tabular Literature Data For The Exo And Endo Isomers Discuss Whi 1 (70.65 KiB) Viewed 49 times
1.0000 Diels alder adduct in chloroform 0.9821 0.9718 0.5065 0.5028 허 46' 8 8 10 12 [rell
Exo adduct (From J. Am. Chem. Soc. 2008, 130(21), 6731-6733.) Cis-5-norbornene-exo-2,3-dicarboxylic anhydride (1). A round-bottom flask was charged with cis-5-norbornene-endo-2,3-dicarboxylic anhydride (198 g). 200 mL 1,2-dicholorobenzene was added, a condenser was attached, and the reaction apparatus was immersed in an oil bath at 185 °C for 4 h. Once cool, the flask was further cooled to 0 °C, and the precipitate was recovered by filtration and washed with hexanes. This crude product was recrystallized from benzene six times to yield 31 g pure exo product (16% yield). 1H NMR: 8 1.42-1.47 (m, 1H), 1.51 (dt, J = 10.2, 1.5 Hz, 1H), 3.01 (d, J = 1.5 Hz, 2H), 3.44-3.47 (m, 2H), 6.34 (t, J =1.8 Hz, 2H). 13C NMR: 8 171.78, 138.14, 48.95, 47.06, 44.30. HRMS: calculated 164.0474, found 164.0468. Endo adduct (From Organometallics 2008, 27(14), 3622-3625.) endo-4-Oxa-tricyclo[5.2.1.02,6]dec-8-ene-3,5-dione, 4g Maleic anhydride (23.0 g, 234.6 mmol, 1.0 equiv) was diluted in toluene (235 mL, 1.0 M). Freshly cracked cyclopentadiene (21.1 mL, 258.0 mmol, 1.1 equiv) was added dropwise at rt and the reaction was stirred for 15 h. The volatiles were evaporated and the white solid required no further purification (36.9 g, 96%). M. p. 164.5-165.5 °C (CDC13) (164-166 °C); H NMR (CDC13, 300 MHz) 6.30 (2H, s), 3.56 (2H, t, J = 12.1 Hz), 3.49 (2H, s), 1.77 (1H, d, J = 9.0 Hz), 1.55 (1H, d, J = 9.0 Hz); 13C NMR (CDC13, 75 MHz) 171.2 (C), 135.5 (CH), 52.7 (CH2), 47.1 (CH), 46.1 (CH); HRMS (EI) expected for C9H303: 164.0473. Found for C3H803: 164.0468.