Alkylidenediquinocyclopropanes and Diarylcyclopropenes and Method for Preparation

A mixture of 1.00 g (2.17 mmol) of bis(3,5-di-tert-butyl-4-hydroxyphenyl)cyclopropenone 4, 0.29 g (4.3 mmol) of malonitrile and 0.02 g of .beta.-alanine in 3.0 ml of freshly distilled acetic anhydride was heated to reflux with stirring for 20 min. A white precipitate formed in the reddish brown solution. The mixture was cooled to room temperature, and the precipitate was collected by filtration and recrystallized from benzene to give 0.62 g (56%) of 6a as pale yellow needles; mp 280-281.degree., (dec); ir (KBr) 3560(m), 2960-2860(m), 2213(m), 2197(m), 1850(w), 1595(m), 1490(s), 1470(m), 1450(w), 1410(s), 1370(s), 1360(s), 1310(s), 1255(s), 1240(m), 1200(w), 1100(m), 1025(w), 925(w), 900(w), 890(sh), 885(w), 780(w), 760(w), 675(2), 655(w), 595 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta.1.52(s, 36HO), 5.98(s,2H), 7.91(s,4H); uv-visible .lambda..sub.max (methanol) 233 nm (log 4.40), 242(4.34), 252(4.29), 299(4.62), 313(4.57), 368(4.54), 396(sh) (4.44); only the longest wavelength absorptions will be shown for the uv-visible spectrum in nonpolar solvents, .lambda..sub.max (benzene) 381 nm, 400(sh); mass spectrum m/e 510.32500 (calc. 510.32462); Anal. Calcd. for C.sub.34 H.sub.42 N.sub.2 O.sub.2 : C, 79.95; H, 8.29; N, 5.49. Found: C, 80.03; H, 8.32; N, 5.43.

A mixture of 3.70 g (8.00 mmol) of 4, 1.81 g (16.0 mmol) of ethylcyanoacetate, and 0.02 g of .beta.-alanine in 12.0 ml of freshly distilled acetic anhydride was refuxed for 8 hr with stirring under nitrogen atmosphere. To the resulting red solution was added 100 ml of benzene and the mixture was washed twice with 200 ml of water and twice with 200 ml of 10% NaHCO.sub.3. After drying (MgSO.sub.4), the organic solution was evaporated in vacuo to give 4.6 g of crude mixture which was then chromatographed over a column which was packed with neutral alumina (100 g) at the bottom and with silica gel (115 g) at the top. Elution with 5% ethereal benzene afforded 1.39 g (31.1%) of crude 6b. Recrystallization from hexane-chloroform gave pale yellow crystals; mp 254-255.degree. (dec); ir (KB4) 3600(s), 3090(w), 2960-2860(m), 2203(m), 1840(w), 1690(s), 1590(m), 1490(s), 1450(sh), 1410(2), 1390(w), 1365(s), 1325(m), 1275 (m-s), 1255(m), 1240(m), 1200(w), 1155(m), 1115(w), 1080(s), 890(w), 810(w), 760(m), 640 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta.1.35(t, 3HO), 1.55(s, 36H), 4.35(q,2H), 5.96(s, 1H), 6.02 (s, 1H), 8.18 (s, 2HO), 8.52(s, 2H); uv-visible .lambda..sub.max (methanol) 233 nm (log E 4.29), 240(sh) (4.26), 250(4.18), 302(4.43), 317(4.50), 368(4.42), 388(sh) (4.29), .lambda..sub.max (cyclohexane) 384 nm, 404(sh); Anal. Calcd for C.sub.36 H.sub.47 NO.sub.4 : C, 77.52; H, 8.49; N, 251. Found: C, 77.43; H, 8.47; N, 2.46.

From successive elution with 50% ethereal benzene, 1.25 g (33.8%) of 4 was recovered.

A mixture of 4.6 g (10.0 mmol) of 4, 4.00 g (40.0 mmol) of 2,4-pentanedione, and 0.1 g of .beta.-alanine in 15.0 ml of acetic anhydride was refluxed for 10 hr and worked up in the same manner as above. The crude product was dissolved in 12 ml of benzene and stirred with 2.0 ml of conc HC10.sub.4 at 0.degree.. The resulting white precipitate was filtered, washed with benzene, and dried under vacuum to give 1,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-(2'-hydroxy-4'-oxo-2'-penten -3-yl)-cyclopropenium perchlorate as a white powder which slowly decomposes at 160-180.degree.; ir (KBr) 3600-3370(br), 2960-2840(m), 1580(m), 1550(w), 1540(w), 1440(w), 1385(s), 1360(s), 1360(s), 1315(w), 1255(m), 1230(w), 1195(w), 1100(br,s), 1020(w), 930(w), 880 cm.sup.-1 (w). The perchlorate salt of the cyclopiopenium ion was dissolved in 10 ml chloroform and 0.5 ml of triethylamine was added with stirring. The resulting yellow solution was washed with water, dried (MgSO.sub.4) and evaporated in vacuo to give 0.79 g (15) of 6c as pale yellow crystals after recrystallization from benzene; mp 230-231.degree. (dec); ir (KBr) 3620(m), 2960-2850(m), 1820(w), 1620(s), 1590(s), 1445(m), 1385(s), 1355(s), 1320(sh), 1305(m), 1260(s), 1235(m), 1190(m), 1075(s), 1020(m), 950(m), 940(sh), 915(w), 890(m), 780(m), 720(w), 680(w), 625 cm.sup.-1 (w); mnr (CDCl.sub.3) .delta.1.50(s, 36H), 2.50(s, 6H), 5.84(s, 2H), 7.96 (s, 4H); uv-vixible, .lambda..sub.max (methanol) 239 nm (log .lambda. 4.34), 272(4.28), 324(4.52), 360(sh) (4.39), .lambda..sub.max (cyclohexane) 364 nm; Anal. Calcd for C.sub.36 H.sub.48 O.sub.4 : C, 79.37; H, 8.88. Found: C, 79.18; H, 8.91.

A mixture of 6.06 g (10.0 mmol) of bis(3,5-di-tert-butyl-4-trimethylsiloxyphenyl)-cyclopropenone and 4.08 g (20.0 mmol) of 1,2,3,4-tetrachloro-1,3-cyclopentadiene in 140 ml of anhydrous methanol was stirred at 45.+-.5.degree. for 1 hr to give a yellow solution and then kept at room temperature for 20 hr. The resulting yellow precipitate was filtered, washed with hexane, and dried under vacuum to afford 0.70 g (8.8%) of 1,2-bis(3,5-di-tert-butyl-4-trimethylsiloxyphenyl)-3-(2',3',4',5'-tetra-ch loro-2',4'-cyclopentadien-1'-ylidene)cyclopropene as a bright yellow powder; mp >230.degree. (no clear mp); ir (KBr) 2960-2840(m), 1825(w-m), 1585(m), 1500(s), 1445(w-m), 1400(s), 1385(m), 1360(sh), 1340(s), 1290(s), 1260(sh), 1235(s), 1195(w), 1115(w), 1005(m), 920(w), 885 (m), 870(s), 835(m), 775(w), 750(w), 650 cm.sup.-1 (w); nmr (CDCl.sub.3) 0.44(s, 18H), 1.46(s, 36H), 8.16(s,4H).

The filtrate was concentrated to ca 70 ml by rotary evaporation and then let stand overnight at -20.degree.. The resulting yellow crystals (4.30 g) were chromatographed over 100 g of silica gel. Elution with benzene afforded 1.32 g (16.7%) of 6d as yellow needles after recrystallization from hexanebenzene; mp 240-241.degree. (dec); ir (KBr) 3600(m), 2970-2850(m), 1830(w), 1590(m), 1500(s), 1445(w), 1410(s), 1355 (m), 1290(s), 1250(w), 1233(m), 1150(m), 1110(w), 1010(m), 915(w), 880(w), 770(w), 675 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.52(s, 36HO), 5.92(s, 2H), 8.07 (s,4H); uv-visible .lambda..sub.max (methanol) 244 nm (lot .epsilon.4.14), 288(sh) (4.11), 312(4.19), 360(4.68); .lambda..sub.max (cyclohexane) 360 nm, .lambda. .sub.max (benzene) 362 nm; mass spectrum m/e 646.19388 (calc 646.19366); Anal. Calcd for C.sub.36 H.sub.42 Cl.sub.4 O.sub.2 : C, 66.67; H, 6.53; Cl, 21.87. Found: C, 66.55; H, 6.59; Cl, 21.79.

Successive elution with 30% ethereal benzene gave 2.95 g (63.9%) of 4.

A mixture of 1.39 g (3.00 mmol) of 4 and 0.80 g (4.9 mmol) of 1,2-dichloro-1-cyclopenten-3,5-dione in 3.6 ml of acetic anhydride was refluxed for 10 min and then cooled at -20.degree. overnight. The resulting precipitate was filtered, washed with ether, and dried under vacuum to give 1.18 g (64.7%) of 6e as yellow powder after recrystallization from CCl.sub.4 -CHCl.sub.3 ; mp >290.degree.; ir (KBr) 3600(m), 2950-2860(m), 1835(w), 1670(sh), 1655(s), 1590(m), 1490(s), 1410(s), 1360(s), 1325(s), 1295(w), 1255(m), 1240(s), 1195(w), 1160(m), 1137(m), 1120(m), 1100(m), 1055(m), 930(w), 920(w), 880(w), 855(w), 810(m), 770(w), 690(w), 650 cm.sup.-1 (w); nmr (CDCL.sub.3) .delta. 1.56(s, 36H), 5.96 (s, 2H), 8.52 (s, 4H); uv-visible .lambda..sub.max (methanol) 241 nm (log .epsilon. 4.56), 278 (4.01), 330(4.64), 362(4.49), 382(sh) (4.41), .lambda..sub.max (cyclohexane) 393 nm; mass spectrum m/e 608.24600 (calc 608,24578); Anal. Calcd for C.sub.36 H.sub.42 Cl.sub.4 O.sub.2 : C, 70.92; H, 6.95; Cl, 11.63. Found: C, 70.86; H, 6.80;, Cl, 11.88.

A mixture of 3.00 g (6.50 mmol) of 4, 1.90 g (13.0 mmol) of 1,3-indanedione, and 0.02 g of .beta.-alanine in 8.0 ml of acetic anhydride was refluxed for 2 hr. The resulting precipitate was filtered; washed with ether to give 2.82 g (73.5%) of 6f as pale pink colored crystals after recrystallization from chloroform; mp 295-296.degree. (dec); ir (KR4) 3596(s), 2950-2850(m), 1834(m), 1653(s), 1480(s), 1409(m), 1353(m), 1236(s), 1197(w), 1141(s), 1121(w), 1020(w), 922(m), 875(m), 810(w), 771)w), 749(w), 730(m), 672(w), 644 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.60(s, 36H0), 5.94(s, 2H), 7.70(m, 4H), 8.69 (s, 4H); uv-visible .lambda..sub.max (methanol) 210 nm (log .epsilon. 4.61), 232(4.62), 285(4.20), 298(4.21), 364(4.73), .lambda..sub.max (cyclohexane) 372 nm; Anal. Calcd for C.sub.40 H.sub.46 O.sub.4 : C, 81.32; H, 7.85. Found: C, 81.23; H, 7.82.

A solution of 1.00 g (3.04 mmol) of potassium ferricyanide in 20 ml of 1N KOH solution was added to a solution of 0.51 g (1.0 mmol) of 6a in 20 ml of chloroform. The deep blue two-phase mixture was stirred vigorously at room temperature for 1 hr under a nitrogen atmosphere. The organic layer was separated, washed with water, dried (MgSO.sub.4) and evaporated in vacuo to give 0.50 g (98%) of 5a as golden plates after recrystallization from hexane; mp 210-215.degree. (dec); ir (KBr) 2960-2860(m), 2227(w), 2217(w), 1753(m), 1600(s), 1525(w), 1510(w), 1470(s), 1360(m), 1345(m), 1260(w), 1115(s), 1020(w), 950(w), 910(m), 830 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.34(s, 18H), 1.38(s, 18H0); 7.45(d,J = 2Hz, 2H), 7.71 (d, J = 2Hz, 2H); uv-visible, .lambda..sub.max (benzene) 319(sh) (3.77), 345(sh) (3.90), 364(4.03), 387(sh) (4.01), 415(sh) (3.88), 498 (sh) (3.96), 548(sh) (4.40), 587(4.79), 609 (4.80), 640(sh) (4.25); mass spectrumm/e 508.31003 (calcd 508.30897); Anal. Calcd for C.sub.34 H.sub.40 N.sub.2 O.sub.2 : C, 80.27; H, 7.93; N, 5.51. Found: C, 80.40; H, 8.09; N, 5.48.

In exactly the same manner as above 0.30 g (0.54 mmol) of 6b was oxidized with excess K.sub.3 Fe(CN).sub.6 to give 0.30 g (100%) of 5b as dark purple plates with golden reflection after recrystallization from hexane-benzene; mp 230-231.degree. (dec); ir (KB4) 2960-2860(m), 2215(w), 1743(m), 1700(m), 1585(s), 1530(w), 1480(w), 1455(m), 1390(w), 1360(m), 1250(s), 1175(w), 1120(w), 1090(s), 1070(m), 1060(m), 935 (w), 905(w), 820(w), 770 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.40(S, 36H), 1.48 (t,3H), 4.46(q, 2H), 7.56 (br,s,2H), 8.06(d,1H0), 8.86 (d, 1H); uv-visible .lambda..sub.max (benzene) 291 nm (log .epsilon. 4.24), 362 (4.01), 550(sh)(4.45 ), 591(4.82), 609(4.80); Anal. Calcd for C.sub.36 H.sub.45 NO.sub.4 : C, 77.80; H, 8.16; N, 2.52. Found: C, 77.70; H, 8.21; N, 2.46.

In the same way, K.sub.3 Fe(CN).sub.6 oxidation of 0.37 g (0.68 mmol) of 6c afforded 0.36 g (97%) of 5c as dark purple plates with golden reflection after recrystallization from hexane; mp 180-190.degree. (dec); ir (KBr) 2960-2840(m), 1730(m), 1685(s), 1645(m), 1590(s), 1540(w), 1500(w), 1480(m), 1450(m), 1390(w), 1360(s), 1255(m), 1200(m), 1090(s), 1025(m), 930(m), 895(m), 820(w), 750(s), 630 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.40(s, 36H), 2.52(s, 6H), 7.54(d, J = 2Hz, 2H), 7.86(d, J = 2Hz, 2H); uv-visible .lambda..sub.max (benzene 296 nm (log .epsilon.4.13), 357(4.03), 557(sh) (4.46), 608(4.70); Anal, Calcd for C.sub.36 H.sub.46 O.sub.4 : C, 79.66; H, 8.54, Found: C, 79.39; H, 8.50.

Similarly oxidation of 0.58 g (0.73 mmol) of 6d with excess K.sub.3 Ke(CN).sub.6 gave 0.57 g (99%) of 5d as dark purple crystals with reddish copper-like reflectance after recrystallization from hexane; mp 200 -210.degree. (dec); ir (KBr) 2960-2840(m), 1700(m), 1590(s), 1520 (w), 1465(m), 1450(m), 1390(w), 1360(m), 1270(s), 1250(m), 1165(m), 1120(w), 1090(s), 1005(w), 895(m), 820(w), 650 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.34(s, 18H), 1.37(s, 18H), 7.48(d, J = 2Hz, 2H), 7.94(d, J = 2Hz, 2H); uv-visible .lambda..sub.max (benzene) 313 nm (log .epsilon. 4.16), 357(4.14), 390(4.10), 672(4.60); Anal. Calcd for C.sub.36 H.sub.40 Cl.sub.4 O.sub.2 : C, 66.88; H, 6.24; Cl, 21.94. Found: C, 66.64; H , 6.40; Cl, 21.75.

In the same way oxidation of 0.46 g (0.76 mmol) of 6e gave 0.45 g (98R) of 5e as dark purple crystals with reddish reflectance after recrystallization from hexane-benzene; mp 255.degree.-260.degree. (dec); ir (KBr) 2960-2840(w), 1745(m), 1860(s), 1575(s), 1470(w), 1440(w), 1380(w), 1355(m), 1250(w), 1220(m), 1195(m), 1120(m), 1080(w), 1010(w), 930(w), 900(m), 810(w), 750 cm.sup.-1 (w); nmr (CDCL.sub.3) .delta. 1.39(s, 18HO), 1.45 (s, 18H), 7.52(d, J = 2Hz, 2H), 8.83(d, J = 2Hz, 2H); uv-visible .lambda..sub.max (benzene) 296 nm (log .epsilon. 4.33), 372(4.06), 390(4.05), 420(sh)(3.95), 550(sh)(4.36), 600(4.77), 621(4.75); Anal. Calcd for C.sub.36 H.sub.40 Cl.sub.2 O.sub.4 : C, 71.16; Y, 664; Cl, 11.67. Found: C, 71.09; H, 6.50; Cl, 11.81.

Similarly, oxidation of 0.59 g (1.00 mmol) of 6f with excess K.sub.3 Fe(CN).sub.6 afforded 0.58g (99%) of 5f as dark reddish purple crystals after recrystallization from hexane-chloroform; mp 236 -238.degree. (dec); ir (KBr) 2960-2860(m), 1750(m), 1677(s), 1580(br,s), 1525(w), 1480(m), 1450(m), 1390(w), 1350(m), 1325(m), 1240(s), 1200(w), 1160(m), 1125(m), 1113(w), 1090(m), 1055(w), 1015(w), 940(w), 910(s) , 890(w), 820(m), 740(s), 685(w), 650 cm.sup.-1 (w); nmr (CDCl.sub.3) .delta. 1.40(s, 18H), 1.50(s, 18H), 7.52(d, J = 2Hz, 2H), 7.87(m, 4H), 9.10(d, J = 2Hz, 2H); uv-visible.lambda..sub.max benzene 290 nm (log .epsilon. 4.30), 307(4.28), 372(4.19), 394(4.15), 423(4.03), 563(sh)(4.42), 610(4.84), 627(sh)(4.80), 668(sh)(4.34); Anal. Calcd for C.sub.40 H.sub.44 O.sub.4 : C, 81.60; H, 7.53. Found: C, 81.73; H, 7.60.

The base titration of compounds 6a-6f was carried out by the following general method: to a well-stirred solution of 0.020 mmol of 6 in 100 ml of spectrograde methanol was added 0.10 N aqueous NaOH in 0.10 ml aliquots by the use of micropipet. The uv-visible spectrum was recorded after each addition of the base and the sample solution was returned to the main branch. No spectral change (beyond experimental error) was observed after adding 0.04 mmol of base. After completing each titration, 0.1 ml of conc HCl was added and regeneration of the original spectrum of 6 was observed; uv-visible spectrum for the dianion of 5a, .lambda..sub.max (methanol) 347 nm (log .epsilon. 4.31), 418 (4.59), 445(4.63); the dianion of 5b, .lambda..sub.max (methanol) 228 nm(sh) (log .epsilon. 4.38), 265(4.25), 300(4.19), 350(4.31), 413(4.64); the dianion of 5c, .lambda..sub.max (methanol) 262 nm (log .epsilon. 4.30), 300(4.23), 401(4.69); the dianion of 5d, .lambda..sub.max (methanol) 264 nm (log .epsilon. 4.02), 300(4.16), 417(4.81); the dianion of 5e, .lambda..sub.max (methanol) 230 nm (log .epsilon. 4.29), 250(4.33), 301(4.22), 406(4.69); the dianion of 5f, .lambda..sub.max (methanol) 228 nm (log .epsilon. 4.61), 286(4.21), 298(4.28), 326(4.24), 413 (4.83 ).

Electrolytic reduction was carried out for the compounds 5a-5f by the following general procedures. About 3 mg of tetrabutylammonium perchlorate and 1 mg of 5 were placed in an electrolytic esr cell. A small piece of glass wool was placed between platinum wire electrodes to slow diffusion. After degassing, dry tetrahydrofuran (distilled from LiAlH.sub.4, stored over Na-K anthracene) was vacuum-distilled into the cell. After three freeze-degas-thaw cycles the cell was sealed and placed in the esr cavity and a minimal current was passed through the cell to generate the esr signal. Coupling constants and g-values were measured using double-cavity technique with Fremmy's salt (potassium nitrosyldisulfonate, g = 2.0057) as reference (Table 2). For 5b an equally-spaced pattern of six (or possibly eight) lines was observed, with splitting of 0.75 G, line width 0.35 G, and g =2.0053. The relative intensities were approximately 1:5:5:5:3:1.

A Princeton Applied Research Model 170 electrochemistry system was used with a three-electrode cell, having platinum-wire working and auxiliary electrodes and a saturated calomel reference electrode. All sample solutions were 1 mM in quinoid compounds with 0.1 M tetrabutylammonium perchlorate as a supporting electrolyte in dichloromethane which had been dried and distilled over P.sub.2 O.sub.5. For all of compounds 5, each wave fulfilled the reversibility criteria for the electrode process:.sup.22 the ratio of cathodic and anodic peak currents, i.sub.pc /i.sub.pa, becomes close to unity as the scan rqte is decreased, and a plot or peak current against square root of the scan rate is linear passing through the origin for both cathodic and anodic peaks in each case. For both waves in all the compounds, the separation between cathodic and anodic peaks decreased with slower scan rate reaching the minimal values of 0.08.about.0.1V, indicating the electron transfer is somewhat slower than the completely reversible case with fast electron transfer..sup.23 From this dependence of the peak separation upon scan rates, the electron transfer rate (k.sub.s) at the platinum-wire electrode surface was calculated to be roughly 5 .times. 10.sup.-3 cm/sec for all the compounds 5 using relationship reported by Nicholson..sup.24 The detailed cyclic voltammetric data are available as microfilm on request.

1. r. west and D. C. Zecher, J. Amer. Chem. Soc., 92, 155 (1970)

3. R. West, D. C. Zecher, S. K. Koster and D. Eggerding, J. Org. Chem., 40, 2295 (1975)

16. E. R. Altwicker, Chem. Rev., 67, 475 (1967)

21. A Roedig and L. Horning, Chem. Ber., 88, 2203 (1955)

22. R. Adams, "Electrochemistry at Solid Electrodes", M. Dekker, New York, N. Y., 1969; R. Nicholson and I. Shain, Anal. Chem., 36, 706 (1964)

23. For a typical completely reversible case, the peak separation is expected to be 0.058V independent on the scan rate (see ref. 22)

24. R. Nicholson, Anal. Chem., 37, 1351 (1965)