Beilstein J. Org. Chem. 2014, 10, 307–315.
then cooled to rt, poured into distilled water (250 mL), and with the deuterium-induced shifts 2Δ = –0.068 for C-2, 3Δ =
shaken with Et2O (3 × 50 mL). The malodorant aqueous layer −0.021 for C-3, and 3Δ = −0.045 ppm for C-1 as caused by the
containing the potassium salt 17 was treated batchwise with =CαD–S(O)–CD3 group incorporated during a run in
NaOCl solution in an amount that sufficed for showing a posi- [D6]DMSO; IR (KBr) ν: 2971, 2959, 2920, 2860, 1627 (w),
tive potassium iodide/starch test for 30 min, at which time this 1484, 1363, 1032, 1022, 968, 748, 677, 505 cm−1; anal. calcd
residual NaOCl was forthwith destroyed by solid NaHSO3 that for C15H20OS (248.39): C, 72.53; H, 8.12; S, 12.91; found: C,
had to be added until the KI/starch test became negative. 72.75; H, 8.25; S, 12.94.
(KMnO4 in place of NaOCl was found to decompose 17.) The
solution was thoroughly stirred with charcoal, then filtered, 2-(p-Methylbenzoyl)-1,1,3,3-tetramethylindane (38a): A
cooled in ice, and acidified with concd. hydrochloric acid. The round-bottomed Schlenk flask (50 mL) was charged with
precipitated acid 10 was extracted with Et2O or (better) pentane 4-bromotoluene (0.563 mL, 4.58 mmol), anhydrous Et2O
(3 × 70 mL). These combined extracts were repeatedly washed (10 mL), and a magnetic stirring bar. The contents were stirred
with distilled water to remove traces of DMSO, dried over and cooled at −78 °C under argon gas cover during the drop-
Na2SO4, and evaporated to leave the almost pure acid 10 as a wise addition of t-BuLi (9.16 mmol) in pentane (6.10 mL), then
white powder (1.31 g, 54%) with mp 188–190 °C (ref [15]: stirred without cooling for 30 min. After the dropwise addition
189–190.5 °C); 1H NMR (CDCl3, 400 MHz) δ 1.41 (s, 6H, 1-/ of acid 10 (400 mg, 1.83 mmol) in anhydrous Et2O (10 mL) to
3-CH3 syn to CO2H), 1.52 (s, 6H, 1-/3-CH3 anti to CO2H), 2.91 this solution of p-methylphenyllithium (34a) and further stir-
(s, 1H, 2-H), 7.16 (AA´ part of an AA´BB´ system, 2H, 4-/7-H), ring at rt for 18 hours, the mixture was poured onto solid CO2,
7.24 (BB´ part, 2H, 5-/6-H) ppm, assigned through the NOESY warmed up, and diluted with aqueous NaOH (1 M, 20 mL). The
correlations 2-H ↔ anti-CH3 ↔ syn-CH3 ↔ 4-/7-H ↔ anti- aqueous layer was shaken with Et2O (3 × 20 mL) and the
CH3; 1H NMR ([D6]acetone, 400 MHz) δ 1.35, 1.48, 2.85, 7.12, combined four Et2O layers were washed with distilled water
7.18 ppm; 13C NMR (CDCl3, 100.6 MHz) δ 27.4 (1-/3-CH3 syn until neutral, dried over Na2SO4, and concentrated to leave the
to CO2H), 30.2 (1-/3-CH3 anti to CO2H), 45.6 (C-1/-3), 64.8 crude nonacidic material (455 mg) consisting mainly of 38a,
(C-2), 122.3 (C-4/-7), 127.3 (C-5/-6), 149.4 (C-3a/7a), 179.1 39a, and toluene (9:1:9). Repeated crystallizations from pentane
(CO2H) ppm, assigned through HSQC; 13C NMR ([D6]acetone, afforded white needles of 38a (isolated yield up to 35%); mp
100.6 MHz) δ 27.7, 30.5, 45.9, 65.2, 123.1, 128.0, 150.5, 173.4 95.5–96.5 °C (methanol); 1H NMR (CDCl3, 400 MHz) δ 1.34
ppm.
and 1.39 (2 s, 2 × 6H, 2 × 1-/3-CH3), 2.42 (s, 3H, p-CH3), 4.10
(s, 1H, 2-H), 7.17 and 7.24 (AA´BB´ system, 2 × 2H, 4-/5-/6-/
1,1,3,3-Tetramethyl-2-(methylsulfinylmethylidene)indane 7-H), 7.28 (broadened d, 3J = 8.3 Hz, 2H, 2 × m-H), 7.88 (dm,
(23). The combined Et2O extracts containing the nonacidic 3J = 8.3 Hz, 2H, 2 × o-H) ppm; 1H NMR (CCl4, 80 MHz) δ
side-products, as obtained in the above preparation of 10 and 1.29, 1.35, 2.39, 3.99, 7.06 (s, 4H), 7.18 (d), 7.80 (d) ppm; 13C
separated from the alkaline aqueous layer, were washed with NMR (CDCl3, 100.6 MHz) δ 21.56 (p-CH3), 28.02 and 30.98 (2
distilled water until neutral, dried over Na2SO4, and evaporated. × 1-/3-CH3), 47.17 (C-1/-3), 64.32 (C-2), 122.34 (C-4/-7),
The remaining brown solid (<977 mg) contained mainly the 127.12 (C-5/-6), 128.28 and 129.34 (2 × C-m and 2 × C-o),
sulfoxides 23 and 33 (3:1) together with a little of 1,1,3,3-tetra- 138.36 (C-ipso), 143.50 (C-p), 149.99 (C-3a/7a), 201.25 (C=O)
methylindan-2-one (24). The pure sample of 23 (284 mg, 10%) ppm; IR (KBr) ν: 2967, 2925, 2862, 1664 (s), 1606, 1480, 1368,
was isolated through extraction into hot, low-boiling petroleum 1228, 1209, 1186, 869, 759 cm−1; anal. calcd for C21H24O
ether (60 mL), filtration, and concentration. Recrystallization (292.42): C, 86.26; H, 8.27; found: C, 86.50; H, 8.41.
afforded almost colorless needles with mp 134–135 °C; 1H
NMR (CDCl3, 400 MHz) δ 1.41 and 1.45 (2 s, 2 × 3H, 2 × The above aqueous NaOH layer was acidified with concd.
3-CH3), 1.51 and 1.73 (2 s, 2 × 3H, 2 × 1-CH3), 2.67 (s, 3H, hydrochloric acid and was shaken with Et2O (3 × 10 mL).
OS-CH3), 6.25 (s, 1H, α-H), 7.17 (AA´ part of an AA´BB´ These combined Et2O extracts were washed with distilled water
system, 2H, 4-/7-H), 7.27 (BB´ part, 2H, 5-/6-H) ppm, assigned until neutral, dried over Na2SO4, and evaporated to leave a
through comparison with the phenylsulfinylmethylidene white powder containing acid 10, p-methylbenzoic acid,
analogue [47]; 1H NMR (DMSO, 200 MHz) δ 1.38 (2 × p-cresol, and diacid 40 (ca. 4:2:2:1).
3-CH3), 1.46 and 1.63 (2 × 1-CH3), 6.47 (α-H), 7.24 (quasi-s,
4-/5-/6-/7-H); 13C NMR (CDCl3, 100.6 MHz) δ 30.12 and 1,1,3,3-Tetramethylindan-2,2-dicarboxylic acid (40): The
31.94 (2 × 3-CH3), 31.54 and 32.95 (2 × 1-CH3), 40.73 mixture of acids obtained above (see 38a) was leached with
(OS–CH3), 48.54 (C-3), 48.76 (C-1), 122.41 and 122.51 (C-4/- pentane, which left the insoluble diacid 40 behind (65 mg, 14%
7), 127.70 and 127.82 (C-5/-6), 128.78 (C-α), 147.04 (C-3a), yield). One recrystallization from hot toluene afforded clean 40
148.23 (C-7a), 174.13 (C-2) ppm, assigned as above in accord (30 mg) but led to the decarboxylation of a portion that
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