Supporting Information for:

Supporting Information for: Photoenolization of 2-(2-Methyl Benzoyl) Benzoic Acid, Methyl Ester: The Effect of The Lifetime of the E Photoenol on the Photochemistry Armands Konosonoks, P. John Wright, Meng-Lin Tsao, Jana Pika, Kevin Novak, Sarah M. Mandel, Jeanette A. Krause Bauer, Cornelia Bohne and Anna D. Gudmundsdóttir* X-Ray Structures Figure S1. Crystal Structure of 7 2 Table S1. Crystal data and structure refinement for 7 3 Figure S2. Crystal Structure of 8 4 Table S2. Crystal data and structure refinement for 8 5 Figure S3. Crystal Structure of 10 6 Table S3. Crystal data and structure refinement for 10 7 1 H-NMR Spectra 8 Figure S4. 1 H-NMR spectra of 4, 6 and 7 8 Figure S5: 1 H-NMR spectra of 8 and 10 9 Molecular Modeling of 3, 3Z and 3E 10 Table S4. Calculated Energies 3, 3Z and 3E 10 Table S5. Optimized Geometry [B3LYP/6-31Gd] 3 11 Table S6. Optimized Geometry [B3LYP/6-31Gd] 3Z 11 Table S7. Optimized Geometry [B3LYP/6-31Gd] 3E 12 Preparation of Ester 3 13 Preparation of Ester 4 14 References 16 S1

X-ray Crystal Structure of 1,2-Bis(2-Methylphenyl)-1,2-Bis(4-Carbmethoxyphenyl)-1,2- Ethanediol, 7. Figure S1. Crystal Structure of 7 S2

Table S1. Crystal data and structure refinement for 7 (C 32 H 30 O 6 ). Empirical formula C 32 H 30 O 6 Formula weight 510.56 Temperature 150(2) K Wavelength 1.54178 Å Crystal system Monoclinic Space group C2/c Unit cell dimensions: a = 10.1964(7) Å α = 90º b = 14.2476(9) Å β = 91.374(4)º c = 18.0359(11) Å γ = 90º Volume, Z 2619.4(3) Å 3, 4 Density (calculated) 1.295 Mg/m 3 Absorption coefficient 0.721 mm -1 F(000) 1080 Crystal size 0.10 x 0.10 x 0.06 mm θ range for data collection 4.91 to 67.75º Limiting indices -12 < h < 12, -17 < k < 16, -21 < l < 21 Reflections collected 7989 Independent reflections 2309 (R int = 0.0539) Completeness to θ = 67.75º 97.1 % Absorption correction multi-scan Max. and min. transmission 0.9580 and 0.9314 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 2309 / 0 / 175 Goodness-of-fit on F 2 1.053 Final R indices [I>2σ(I)] R1 = 0.0483, wr2 = 0.1331 R indices (all data) R1 = 0.0599, wr2 = 0.1411 Largest diff. peak and hole 0.212 and -0.259 eå -3 S3

Figure S2. Crystal Structure of 8. S4

Table S2. Crystal data and structure refinement for C 16 H 12 O 4 : 2-(3-oxo-1,3-dihydroisobenzofuran-1-yl)-benzoic acid methyl ester, 8. Empirical formula C 16 H 12 O 4 Formula weight 268.26 Temperature 150(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions: a = 8.0922(9) Å α = 111.314(2)º b = 8.6918(9) Å β = 91.303(2)º c = 10.0834(10) Å γ = 108.706(2)º Volume, Z 617.96(11) Å 3, 2 Density (calculated) 1.442 Mg/m 3 Absorption coefficient 0.104 mm -1 F(000) 280 Crystal size 0.36 x 0.12 x 0.11 mm θ range for data collection 2.69 to 29.55º Limiting indices -11 < h < 10, -11 < k < 11, -13 < l < 13 Reflections collected 6612 Independent reflections 3122 (R int = 0.0258) Absorption correction Multi-scan Max. and min. transmission 0.9886 and 0.9635 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 3122 / 0 / 181 Goodness-of-fit on F 2 1.032 Final R indices [I>2σ(I)] R1 = 0.0469, wr2 = 0.1073 R indices (all data) R1 = 0.0639, wr2 = 0.1145 Largest diff. peak and hole 0.308 and -0.236 eå -3 S5

X-ray Crystal Structure of 2(2-Formyl-benzoyl)-benzoic acid methyl ester, 10. Figure S3. X-ray Structure of 10. S6

Table S3. Crystal data and structure refinement for C 16 H 12 O 4 : 10 Empirical formula C 16 H 12 O 4 Formula weight 268.26 Temperature 297(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions: a = 7.7270(4) Å α = 112.124(1)º b = 9.1842(5) Å β = 109.389(1)º c = 11.0217(5) Å γ = 91.253(1)º Volume, Z 673.76(6) Å3, 2 Density (calculated) 1.322 Mg/m 3 Absorption coefficient 0.095 mm -1 F(000) 280 Crystal size 0.50 x 0.28 x 0.10 mm θ range for data collection 2.14 to 28.34º Limiting indices -10 < h < 10, -12 < k < 12, -14 < l < 14 Reflections collected 9361 Independent reflections 3361 (R int = 0.0125) Completeness to θ = 28.34º 99.8 % Absorption correction Multi-scan Max. and min. transmission 0.9905 and 0.9538 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 3361 / 0 / 217 Goodness-of-fit on F 2 1.035 Final R indices [I>2σ(I)] R1 = 0.0382, wr2 = 0.0994 R indices (all data) R1 = 0.0534, wr2 = 0.1108 Largest diff. peak and hole 0.198 and -0.129 eå -3 S7

4 6 7 Figure S4. 1 H-NMR spectra of 4; 6 and 7. S8

8 10 Figure S5. 1 H-NMR spectra of 8 and 10. S9

Table S4. Calculated Energies 3, 3Z and 3E Compound Theory Total Energy (Hartrees) # of Imaginary Frequencies 3 B3LYP/6-31G(d) 0 3E 843.75383277 0 3Z 843.75696792 0 Table S5. Optimized Geometry [B3LYP/6-31Gd] 3 --------------------------------------------- Atomic Coordinates (Angstroms) Number X Y Z --------------------------------------------- 6 3.051120-2.317510 0.385037 6 1.747398-2.273124-0.108443 6 1.093641-1.051672-0.300942 6 1.786222 0.145207-0.025919 6 3.097968 0.092796 0.466567 6 3.726522-1.131854 0.678747 1 3.539377-3.276587 0.535068 1 1.219528-3.191647-0.346936 1 3.622368 1.020530 0.665412 1 4.743655-1.159658 1.059051 6-0.329681-1.108844-0.828673 8-0.523589-1.642034-1.910799 6-1.443163-0.634615 0.050457 6-1.263609-0.658656 1.442313 6-2.291901-0.298546 2.310459 6-3.513981 0.112414 1.782047 6-3.694789 0.154365 0.398571 6-2.684416-0.220882-0.493529 1-0.309422-0.979638 1.849108 1-2.137429-0.336551 3.385197 1-4.326667 0.404730 2.442170 1-4.647327 0.489747-0.004919 6-2.938813-0.136676-1.978952 1 2.992703-1.130216-2.433322 1-3.879466 0.389431-2.172220 1-2.128222 0.394660-2.487069 6 1.149016 1.453279-0.350888 8 0.176743 1.586374-1.069498 8 1.785012 2.497087 0.225204 6 1.245804 3.791346-0.089234 1 0.207723 3.863954 0.244954 1 1.873201 4.505219 0.445105 1 1.286044 3.972446-1.166574 --------------------------------------------------------------------- S10

Table S6. Optimized Geometry [B3LYP/6-31Gd] 3Z ---------------------------------------------- Atomic Coordinates (Angstroms) Number X Y Z -------------------------------------------- 6 4.119629-1.284133-0.403780 6 2.801791-1.391815-0.701568 6 1.818735-0.458984-0.165259 6 2.264763 0.409474 0.960442 6 3.711266 0.567250 1.117025 6 4.590791-0.242591 0.483559 1 4.838432-1.965344-0.851208 1 2.448200-2.136371-1.404618 1 4.056218 1.316651 1.825613 1 5.658675-0.135037 0.656682 6 1.443522 0.966055 1.884694 1 0.373214 0.803492 1.900674 1 1.851635 1.593652 2.672485 6 0.575396-0.427399-0.748875 6-0.453148 0.641686-0.550043 6-0.051396 1.963434-0.816278 6-0.933158 3.033336-0.718319 6-2.257657 2.816040-0.329062 6-2.682892 1.522861-0.058120 6-1.806792 0.428144-0.181773 1 0.978917 2.137399-1.106659 1-0.587210 4.037391-0.948322 1-2.953138 3.646105-0.246397 1-3.708537 1.337310 0.239209 8 0.300458-1.324462-1.744141 1-0.610665-1.656947-1.577425 6-2.352590-0.933213 0.060243 8-1.924287-1.970646-0.432579 8-3.416435-0.931247 0.881605 6-4.030978-2.212314 1.112206 1-3.317402-2.898249 1.574663 1 4.865929-2.013407 1.783952 1 4.384002-2.642783 0.171730 ---------------------------------------------------- S11

Table S7. Optimized Geometry [B3LYP/6-31Gd] 3E ---------------------------------------------- Atomic Coordinates (Angstroms) Number X Y Z -------------------------------------------- 6 3.106366 1.132806 1.643849 6 1.951311 0.966977 0.953552 6 1.793453-0.029014-0.098468 6 2.986553-0.872089-0.412016 6 4.185578-0.632831 0.391328 6 4.258340 0.314826 1.353042 1 3.160288 1.869545 2.440898 1 1.088747 1.562698 1.227989 1 5.047688-1.258058 0.171270 1 5.175381 0.459591 1.918202 6 0.564041-0.191394-0.703024 8 0.379655-1.173853-1.625413 6-0.582022 0.754695-0.514834 6-0.344770 2.114734-0.788140 6-1.338763 3.081364-0.663279 6-2.619254 2.716509-0.246808 6-2.887171 1.381158 0.029493 6-1.897968 0.393436-0.114352 1 0.648438 2.405952-1.112437 1-1.111506 4.117920-0.897064 1-3.402645 3.461584-0.144202 1-3.877461 1.081429 0.352709 6-2.297326-1.017729 0.137539 8-1.817375-2.002139-0.412493 8-3.292999-1.126177 1.031840 6 3.072020-1.815516-1.389031 1 2.261653-2.058205-2.056594 1 4.008036-2.354147-1.516829 1-0.524922-1.541765-1.492809 6-3.772865-2.462049 1.275471 1-4.156656-2.904971 0.353057 1-2.967899-3.088542 1.666500 1-4.568523-2.350970 2.011910 ---------------------------------------------------- S12

Preparation of 2-(2-methylbenzoyl) benzoic acid, methyl ester, 3: Ester 3 was prepared by a method of Hellwinkel et al. 1 2-(2-Methylbenzoyl) benzoic acid: To a well-stirred suspension of phthalic anhydride (14.8 g, 0.10 mol) in a mixture of anhydrous benzene (120 ml) and anhydrous diethyl ether (40 ml) in a 500-mL three-necked round bottom flask equipped with a reflux condenser and cooled in an ice bath was added 2 M solution of o-tolylmagnesium bromide (52 ml, 0.10 mol) over 60 minutes. The mixture was refluxed for 90 minutes, and allowed to stir at room temperature overnight. The yellow reaction mixture was poured on ice/concentrated hydrochloric acid (200 ml/20 ml), and the resulting mixture extracted with diethyl ether (2 50 ml). The organic phase was washed with brine (2 50 ml), dried over anhydrous magnesium sulfate, and evaporated to yield 2-(2-methylbenzoyl) benzoic acid (20 g, 0.083 mol, 83% yield) as an orange oil which solidified. The acid was recrystallized from ethyl acetate to give colorless crystals. Mp: 125-130.5 C (lit.: 2 mp: 127-130 C). IR (KBr): 2967, 1715, 1635, 1568, 1251, 933, 761, 736 cm -1. 1 H NMR (250 MHz, CDCl 3 ): δ 2.62 (s, 3H), 7.10-7.45 (m, 6H), 7.54-7.68 (m, 2H), 8.02 (d, 1H) ppm. 2-(2-methylbenzoyl) benzoic acid, methyl ester, 3: Without further purification, 2-(2- methylbenzoyl) benzoic acid (20 g, 0.083 mol) and concentrated sulfuric acid (4 ml, 0.075 mol) were heated under reflux in methanol (250 ml) for 52 h. The reaction mixture was added to a saturated sodium bicarbonate solution (500 ml), and the resulting mixture extracted with diethyl ether (4 100 ml). The organic phase was washed with water (2 50 ml) dried over anhydrous magnesium sulfate to give 3 (16.9 g, 0.07 mol, 80% yield) as a red oil, which was purified using a silica gel column eluted with 10% ethyl acetate in hexane to yield a colorless oil. The mass spectra of 3 matches that in the literature. 4 S13

Mp: 34-35 C (lit.: 3 mp: 37-39 C). IR (neat): 2952, 1724, 1671, 1434, 1279, 1126, 928, 738 cm -1. 1 H NMR (250 MHz, CDCl 3 ): δ 2.65 (s, 3H), 3.61 (s, 3H), 7.12-7.21 (m, 2H), 7.26-7.40 (m, 2H), 7.46 (m, 1H), 7.52-7.61 (m, 2H), 7.92 (m, 1H) ppm. 13 C NMR (60 MHz, CDCl 3 ): δ 21.4, 52.3, 125.4, 128.6, 129.9, 130.1, 130.2, 131.3, 131.8, 131.9, 132.0, 136.8, 139.8, 142.5, 167.1, 198.0 ppm. MS (EI) m/z (rel. intensity): 254 (M +, 4), 239 (2), 222 (100), 194 (100), 165 (63), 119 (33), 91 (51), 77 (20). Preparation of 4-(2-methyl-benzoyl)-benzoic acid methyl ester (4). Terephthalic acid monomethyl ester. A solution of potassium hydroxide (5.6 g, 0.1 mol) in a mixture of water (5 ml) and methanol (100 ml) was added over 2 hours to a suspension of terephthalic acid dimethyl ester (21.4 g, 0.11 mol) in a mixture of methanol (100 ml) and diethyl ether (100 ml). The white suspension was stirred at room temperature for 17 hours, and refluxed for 4 hours. Litmus paper indicated that the reaction mixture was at ph 7, and thus the white precipitate was filtered, dissolved in water (800 ml), filtered to clarity, and acidified with concentrated hydrochloric acid. The white precipitate of terephthalic acid monomethyl ester was filtered, washed with water, and dried to yield 14.46 g (80.3 mmol, 73% yield): The melting point and IR and NMR spectra of terephthalic acid monomethyl ester match the ones in the literature. 5-7 Mp: 219-222ºC (lit.: 7 218-220ºC). IR (KBr): 3100-2300, 1721, 1690, 1277 cm -1. 1 H NMR (CD 3 OD): δ 8.10 (s, 4H), 3.93 (s, 3H) ppm. 4-Chlorocarbonyl-benzoic acid methyl ester was prepared following a procedure by Firestone. 8 Terephthalic acid monomethyl ester (14.40 g, 80 mmol) was refluxed with anhydrous benzene (10 ml), a drop of pyridine, and thionyl chloride (40 ml) for 5 hours. The clear mixture S14

was then distilled under reduced pressure until no more distillate came over. Anhydrous benzene (25 ml) was added and distillation continued. The colorless residue was frozen with liquid nitrogen and pumped under vacuum and then warmed to room temperature to give 4- chlorocarbonyl-benzoic acid methyl ester (14.38 g, 73 mmol, 91% yield) as a white crystalline mass. The melting point as well as IR and NMR spectra matched those in the literature. 5, 7 Mp: 52-56 C. (lit.: 5 55ºC). IR (KBr): 1778, 1738, 1723, 1280 cm -1. 1 H NMR (250 MHz, CDCl 3 ): δ 8.18 (s, 4H), 3.98 (s, 3H) ppm. 4-(2-Methyl-benzoyl)-benzoic acid methyl ester (4). A solution of o-bromotoluene (4.08 g, 23.9 mmol) in a mixture of anhydrous diethyl ether (15 ml) and anhydrous benzene (5 ml) was added dropwise over one hour to magnesium turnings (0.58 g 23.9 mmol). The Grignard reagent was refluxed for 20 minutes, cooled in an ice bath, and anhydrous cadmium chloride (2.61 g, 14.2 mmol) added in one portion. The resulting gray mixture was heated under reflux for 45 minutes. The diethyl ether was then distilled until a dark gray slurry formed and distillation became slow. Anhydrous benzene (20 ml) was then added. A solution of 4-chlorocarbonyl-benzoic acid, methyl ester (4.70 g, 23.7 mmol) in anhydrous benzene (10 ml) was added to the hot solution over 10 minutes. The mixture was heated under reflux for 3 hours, cooled to room temperature, and concentrated hydrochloric acid (10 ml) added followed by water (20 ml). The layers were separated, the aqueous phase extracted with diethyl ether (3 50 ml), the organic layer washed with aqueous sodium bicarbonate (2 50 ml) and brine (2 50 ml), dried over anhydrous magnesium sulfate, and evaporated to give a yellow oil. The crude product was purified by column chromatography to give 4-(2-methyl-benzoyl)-benzoic acid methyl ester, 4, (2.63 g, 10.4 mmol, 44%) an off-white crystalline mass: S15

Mp: 47-52ºC. IR (neat) 2953, 1725, 1667, 1279 cm -1. 1 H NMR (250 MHz, CDCl 3 ) δ: 8.12 (d, 8 Hz, 2H), 7.84 (d, 8 Hz, 2H) 7.45-7.26 (m, 4H) 3.95 (s, 3H), 2.35 (s, 3H) ppm. 13 C NMR (60 MHz, CDCl 3 ): δ 198.0, 166.4, 141.4, 138.0, 137.3, 133.9, 131.3, 130.9, 130.0, 129.9, 129.7, 129.6, 129.0, 125.4, 52.5, 20.2 ppm. MS (EI) m/z (relative intensity): 253 (M-1, 6), 239 (19), 223 (10), 195 (100), 177 (15), 165 (20), 152 (6), 135 (7), 119 (31), 91 (52), 65 (27). HRMS: m/z calcd. for C 16 H 15 O 3, [M+H] + : 255.1021. Found: 255.1012. Reference: 1. Hellwinkel, D., Bohnet, S. Chem. Ber. 1987, 120, 1151. 2. Newman, M. S.; McCleary, C. D. J. Am. Chem. Soc. 1941, 63, 1537. 3. Weiss; K. Monatsh. Chem. 1924, 210. 4. Ballantine; J. A.; Pillinger; C. T. Org. Mass. Spectrom. 1968, 1, 447. 5. Exner, O.; Svatek, E. Collect. Czech. Chem. Commun. 1971, 36, 534. 6. Kasina, S. Ng, K. W.; Nematollahi, J. J. Pharm. Sci. 1974, 63, 1155. 7. Yli-Kauhaluoma, J. T.; Ashley, J. A.; Lo, C.-H.; Tucker, L.; Wolfe, M. M.; Janda, K. D. J. Am. Chem. Soc. 1995, 117; 7041. 8. Firestone, R. A.; Maciejewitz, N. S.; Christensen, B. G. J. Org. Chem., 1974, 39, 3384. S16