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Helvetica Chimica Acta ± Vol. 84 (2001)
52.2 (2q, 2 MeO); 57.5 (d, C(3)); 69.2 (s, C(2)); 126.70, 127.0 (2d, 2 C(4')); 126.79, 127.6, 128.4, 128.5 (4d, 2 C(2'/
6'), 2 C(3'/5')); 142.4, 147.7 (2s, 2 C(1')); 170.8, 171.3 (2s, 2 CO). Anal. calc. for C20H20O4S (356.43): C 67.39, H
5.66, S 9.00; found: C 67.66, H 5.53, S 9.17.
2.5. Tetramethyl 2,2-Diphenylthiolane-3,3,4,4-tetracarboxylate (16). The reaction of tetramethyl ethyl-
enetetracarboxylate (7.70 mmol) and 1 (5.23 mmol) in THF (14 ml), and CH2Cl2 (15 ml) furnished dimer 6
(362 mg, 33%) and 16 (695 mg, 28%); 16 was separated from the excess of dipolarophile by fractional
crystallization from MeOH. M.p. 129 ± 1318 (MeOH). IR: 1245vs, 1261vs, 1287s (C O); 1730vs, 1743vs, 1755vs,
1760vs (CO). 1H-NMR (60 MHz): 3.48 (s, 2 MeO); 3.58 (s, 2 MeO), 3.87 (s, CH2(5)); 7.08 ± 7.75 (m, 10 arom.
H). 13C-NMR (20.2 MHz): 35.8 (t, C(5)); 52.5, 53.2 (2q, 2 MeO); 71.1, 73.8, 76.8 (3s, C(2), C(3), C(4)); 126.8,
130.6 (2 br. d, 10 arom. C); 144.4 (s, 2 C(1')); 167.6, 168.6 (2s, 4 CO). MS (808): 472 (19, M ), 413 (16, [M
CO2Me] ), 243 (69), 212 (52, 17), 211 (47, 18), 198 (97, 3 ), 165 (100, 21), 121 (82, 22), 113 (19), 105 (17), 77 (27,
Ph ), 59 (39, MeOCꢀO ). Anal. calc. for C24H24O8S (472.50): C 61.00, H 5.12, S 6.79; found: C 61.33, H 5.05, S
6.78.
2.6. 2,2-Diphenylthiolane-3-carbonitrile (23). Acrylonitrile (34 mmol) and 1 (3.75 mmol) in THF (10 ml)
afforded 23 (753 mg, 76%). M.p. 141 ± 1438 (CHCl3/MeOH). 1H-NMR (360 Hz): 2.34, 2.48 (C and D of
ABCDX, visible 14 and 12 lines, resp.; clarified by double resonance experiments, J(4A,4B) 13.0, CH2(4));
3.16, 3.23 (AB of ABCDX, 14 lines, J(5A,5B) 10.8, CH2(5)); 3.95 (X of ABCDX, dd, J 5.6, 9.0, H C(3));
7.23 ± 7.42 (m, 8 arom. H); 7.50 ± 7.55 (m, 2 arom. H). 13C-NMR (20.2 MHz): 29.7, 32.3 (2t, C(4), C(5)); 43.2 (d,
C(3)); 68.0 (s, C(2)); 118.6 (s, CN); 127.4, 127.7 (2d, 2 C(4')); 126.6, 127.9, 128.5, 128.8 (4d, 2 C(2'/6'), 2 C(3'/5'));
141.8, 143.6 (2s, 2 C(1')). MS (708): 265 (91, M ), 232 (4.2, [M SH] ; HR: calc.: 232.1123; found: 232.1103; 13
C
0.78/0.86), 212 (41, C14H12S , 17), 211 (100, C14H11S , 18; HR: calc.: 211.0579; found: 211.0579), 205 (4, [M
SCH2CH2] , 26; HR: calc.: 205.0889; found: 205.0905), 204 (7, C15H10N , 27; HR: calc.: 204.0811; found:
204.0807), 203(6), 198 (8, 3 ), 188 (11, [M Ph] ), 179 (12, C14H11 , 20), 178 (17), 165 (23, 21), 121 (11, 22), 115
(5), 77 (5, Ph ). Anal. calc. for C17H15NS (265.36): C 76.94, H 5.70, N 5.28, S 12.08; found: C 77.07, H 5.70, N 5.19,
S 11.80.
2.7. 2,2-Diphenylthiolane-3,4-trans-dicarbonitrile (24). Dihydrothiadiazole 1 (2.92 mmol) was reacted with
fumaronitrile (3.19 mmol) in THF (10 ml) at 408. The low solubility of 24 (771 mg, 91%) facilitated the
isolation. M.p. 198 ± 2008 (acetone/Et2O). IR: 1444s, 1490s, 1581m, 1592m (arom. ring vibration), 2247m
(CꢀN). 1H-NMR (400 MHz): simulation of the exper. ABCX spectrum of the ring protons by DavinX [14]
(Fig.); criteria of assignment: H C(3) at highest frequency shows only one vicinal coupling, and H C(4) three
1
vicinal couplings; the negative sign is expected for J(5A,5B); substituent increments on H chemical shifts for
geminal CN (1.13), cis-vicinal CN (0.39), trans-vicinal CN (0.58), evaluated from pyrazolidine derivatives
[39], allow us to distinguish HA C(5) and HB C(5) of 24 on the basis of the d(H) of 23; Jcis > Jtrans is unreliable
in saturated five-membered rings and is violated by J(4,5A) < J(4,5B). 13C-NMR: 32.5 (t, C(5)); 34.4 (d, C(4));
46.8 (d, C(3)); 67.0 (s, C(2)); 115.4, 116.9 (2s, 2 CN); 126.4, 2 Â 128.4, 128.7, 2 Â 129.0 (6d, 10 arom. C); 139.8,
141.1 (2s, 2 C(1'). Anal. calc. for C18H14N2S (290.37): C 74.75, H 4.86, N 9.65, S 11.04; found: C 74.67, H 4.71, N
9.65, S 11.11.
2.8. 2,2-Diphenylthiolane-3,3,4,4-tetracarbonitrile (25). Compound 1 (4.60 mmol) and TCNE (5.35 mmol)
in THF (14 ml) were stirred at 458 for 6 h to produce 25 (1.45 g, 93%). M.p. 177 ± 178.58 (CHCl3). IR: 698s,
744s, 752s (arom. CH out-of-plane deform.); 1447s, 1496m, 1584w (arom. ring vibration), 2245w (CꢀN).
1H-NMR (80 MHz): 3.93 (s, CH2(5)); 7.15 ± 7.53 (m, 10 arom. H); application of substituent increments for cis-
vicinal- and trans-vicinal-CN, mentioned above, to the introduction of a second 4-CN into 24 leads to a
prediction for CH2(5) of 25 at 3.91 and 3.97, in good agreement with the exper. value. 13C-NMR (20.2 MHz,
(D6)acetone): 38.6 (t, C(5)); 48.7 (s, C(4)); 58.7 (s, C(3)); 73.8 (s, C(2)); 111.6, 111.9 (2s, 4 CN); 128.6, 130.0,
130.5 (3d, 10 arom. C); 140.0 (s, 2 C(1')). MS (1508): 340 (4, M ), 339 (14, [M H] ), 230 (12, [M
SCH2C(CN)2], 229 (12), 212 (52, 17), 211 (100, 18), 203 (11), 179 (15, 20), 178 (14), 165 (46, 21), 135 (14,
[212 Ph] ), 121 (24, 22), 78 (13, PhH ), 77 (24, Ph ). Anal. calc. for C20H12N4S (340.39): C 70.57, H 3.55, N
16.46, S 9.42; found: C 70.70, H 3.67, N 16.27, S 9.46.
Attempts of Interference with an Intermediate [40]. In parallel experiments, 2 was reacted with 1.1 equiv. of
1
TCNE in dry THF, in THF 2 vol-% of H2O, and in THF 2 vol-% of MeOH. H-NMR Analysis with sym-
C2H2Cl4 as weight standard indicated 25 in 89, 92, and 94% yields, respectively.
2.9. 2,2-Diphenylthiolane-3,4-cis-dicarboxylic Anhydride (28) [41]. Compound 1 (10.0 mmol) in THF
(20 ml) and maleic anhydride (10.0 mmol) in acetone (10 ml) were reacted at 408 and gave 28 (2.98 g, 96%).
M.p. 126 ± 1288 (Et2O). 1H-NMR (60 MHz): 2.64 (dd, J 7.5, 12.8, HA C(5)); 3.23 (d, J 12.8, HB C(5)); 3.78
(t, J(4,5A) J(3,4) 7.5, H C(4)); 4.33 (d, J 7.5, H C(3)); 7.22 (br. m, 10 arom. H). Anal. calc. for
C18H14O3S (310.36): C 69.66, H 4.55; found: C 69.38, H 4.41.