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3
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33646459693
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See also, b
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See also, b) F. Gavina; A.M. Costero; M.R. Andreu; S.V. Luis, J. Am. Chem. Soc. 110, 6112 (1988).
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(1988)
J. Am. Chem. Soc
, vol.110
, pp. 6112
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Gavina, F.1
Costero, A.M.2
Andreu, M.R.3
Luis, S.V.4
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10
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0008337355
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f) A.M. Bernard; M.T. Coceo; C. Congiu; V. Onnis; P. P. Piras, Heterocycles, 41, 1479 (1995).
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(1995)
Heterocycles
, vol.41
, pp. 1479
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Bernard, A.M.1
Coceo, M.T.2
Congiu, C.3
Onnis, V.4
Piras, P.P.5
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12
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36249008675
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M. Ohno; S. Eguchi, Directed Synthesis of Biologically Interesting Heterocycles with Squaric Acid (3,4-Dihydroxy-3-cyclobutene-1,2-dione) Based Technology in Top. Heterocycl. Chem., 6 Bioactive Heterocycles I (Eguchi, S. ed.), Springer-Verlag, Heidelberg, 2006, pp. 1-37.
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M. Ohno; S. Eguchi, Directed Synthesis of Biologically Interesting Heterocycles with Squaric Acid (3,4-Dihydroxy-3-cyclobutene-1,2-dione) Based Technology in Top. Heterocycl. Chem., 6 "Bioactive Heterocycles I" (Eguchi, S. ed.), Springer-Verlag, Heidelberg, 2006, pp. 1-37.
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16
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36248964274
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4). Evaporation of the solvent left the residue, which was chromatographed on a silica gel column (hexane/AcOEt 15/1) to give 5 as oil.
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4). Evaporation of the solvent left the residue, which was chromatographed on a silica gel column (hexane/AcOEt 15/1) to give 5 as oil.
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17
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36249003504
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13C NMR δ 15.3, 15.5, 63.4, 70.6, 104.6, 127.7, 128.1, 129.0, 129.3, 129.8, 178.3, 185.5.
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13C NMR δ 15.3, 15.5, 63.4, 70.6, 104.6, 127.7, 128.1, 129.0, 129.3, 129.8, 178.3, 185.5.
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18
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36248994304
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Patented compound, mp 127.5-129.5°C (cf. Umio, S.; Kariyone, K.; Nishida, M. Chem. Abstr. 71, 12859 (1969): observed mp 127.5-129.5°C.
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Patented compound, mp 127.5-129.5°C (cf. Umio, S.; Kariyone, K.; Nishida, M. Chem. Abstr. 71, 12859 (1969): observed mp 127.5-129.5°C.
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19
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36248969718
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2.
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2.
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20
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36249032675
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13C NMR δ 14.2, 15.3, 68.5, 69.4, 114.1, 128.50, 128.54, 129.4, 129.9, 155.7, 182.5, 183.3.
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13C NMR δ 14.2, 15.3, 68.5, 69.4, 114.1, 128.50, 128.54, 129.4, 129.9, 155.7, 182.5, 183.3.
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21
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36249017494
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Heat of formation was compared for a case of R = Pr (13d and 16d) by AM1 calculation; 13d is slightly more stable (0.5 kcal/mol) in syn-form (as is depicted in Scheme 4) than in anti-form, and much more stable (8.5 kcal/mol) than antiaromatic form of 16d. These results suggest that the syn-form is likely stereochemistry of 13, and 16 is unlikely tautomer (if not so, the cyclization would have proceeded without difficulty).
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Heat of formation was compared for a case of R = Pr (13d and 16d) by AM1 calculation; 13d is slightly more stable (0.5 kcal/mol) in syn-form (as is depicted in Scheme 4) than in anti-form, and much more stable (8.5 kcal/mol) than antiaromatic form of 16d. These results suggest that the syn-form is likely stereochemistry of 13, and 16 is unlikely tautomer (if not so, the cyclization would have proceeded without difficulty).
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22
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36248934339
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All of the products (7, 8, 13-15, 18) derived from 6 gave satisfactory spectral data. A typical procedure and spectral data were as follows: A solution of 5a (80 mg, 0.3 mmol) in dry p-xylene (5 mL) was refluxed for 30 min under a nitrogen atmosphere, and the product was cooled and treated directly with 11 e (0.1 mL, 1.5 mmol) at room temperature for 1 h. After evaporation of the solvent, the residue was chromatographed on a silica gel column (hexane/AcOEt 5/1) to give 18e (30 mg, 45, IR (KBr) 1685, 1625 cm-1; 1H NMR (DMSO-d6)δ 3.19 (2 H, dt, J, 6.4, 2.0 Hz, 3.65 (2 H, t, J, 6.4 Hz, 7.15-7.78 (5 H, m, 7.78 (1 H, br s, 9.74 (1 H, br s, 13C NMR (DMSO-d6) δ 38.7, 45.5, 97.7, 125.6, 127.1, 128.3, 131.8, 138.3, 153.3, 172.2; MS (EI) m/e (rel. intensity) 213 (M, 100, 212 (49, 184 (11, 157(10, 12910
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+, 100), 212 (49), 184 (11), 157(10), 129(10).
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