A Simple and Green Approach
for the Synthesis of Tetrahydrobenzo[a]-xanthen-11-one
Derivatives Using Tetrabutyl Ammonium Fluoride in Water

Shijay Gao; Chen Hsuan Tsai; Ching-Fa Yao

doi:10.1055/s-0028-1088214

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Synlett 2009(6): 949-954
DOI: 10.1055/s-0028-1088214

LETTER

A Simple and Green Approach for the Synthesis of Tetrahydrobenzo[a]-xanthen-11-one Derivatives Using Tetrabutyl Ammonium Fluoride in Water

Shijay Gao, Chen Hsuan Tsai, Ching-Fa Yao*
Department of Chemistry, National Taiwan Normal University, 88 Tingchow Road, Section 4, Taipei 11677, Taiwan, Republic of China
Fax: +886(2)29324249; e-Mail: cheyaocf@ntnu.edu.tw;

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Publication History

Received 18 September 2008
Publication Date:
16 March 2009 (online)

Abstract
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Abstract

An efficient and simple procedure for the synthesis of 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives has been described. This one-pot multicomponent reaction involves the reaction of aldehydes, 2-naphthol, and cyclic 1,3-diketones in the presence of catalytic amount of recyclable TBAF in water.

Key words

tetrabutylammonium fluoride - recyclable - water - tetrahydrobenzo[a]xanthen-11-one

References and Notes

1 Wender PA. Handy ST. Wrigth DL. Chem. Ind. 1997, 765

Google Scholar
2a Nair V. Vinod AU. Rajesh C. J. Org. Chem. 2001, 66: 4427

Google Scholar
2b Bora U. Saikia A. Boruah RC. Org. Lett. 2003, 5: 435

Google Scholar
2c Demaude T. Knerr L. Pasau P. J. Comb. Chem. 2004, 6: 768

Google Scholar
2d Fayol A. Zhu J. Org. Lett. 2004, 6: 115

Google Scholar
2e Nair V. Menon RS. Beneesh PB. Sreekumar V. Bindu S. Org. Lett. 2004, 6: 767

Google Scholar
2f Nair V. Bindu S. Sreekumar V. Rath NP. Org. Lett. 2005, 5: 665

Google Scholar
2g Nair V. Sreekumar V. Bindu S. Suresh E. Org. Lett. 2005, 7: 2297

Google Scholar
2h Siamaki AR. Arndtsen BA. J. Am. Chem. Soc. 2006, 128: 6050

Google Scholar
2i Cui S.-L. Lin X.-F. Wang Y.-G. Org. Lett. 2006, 8: 4517

Google Scholar
2j Xu X. Cheng D. Li J. Guo H. Yan J. Org. Lett. 2007, 9: 1585

Google Scholar
2k Cui S.-L. Wang J. Wang Y.-G. Org. Lett. 2007, 9: 5023

Google Scholar
3a Mori A. Kawashima J. Shimada T. Suguro M. Hirabayashi K. Nishihara Y. Org. Lett. 2000, 2: 2935

Google Scholar
3b Barluenga J. Andina F. Fernandez-Rodriguez MA. Garcia-Garcia P. Merino I. Aquilar E. J. Org. Chem. 2004, 69: 7352

Google Scholar
4 Crouch RD. Tetrahedron 2004, 60: 5833

Crossref Google Scholar
5a Capperucci A. Degl’Innocenti A. Leriverend C. Metzner P. J. Org. Chem. 1996, 61: 7174

Google Scholar
5b Sirol S. Courmarcel J. Mostefai N. Riant O. Org. Lett. 2001, 3: 4111

Google Scholar
5c Denmark SE. Sweis RF. J. Am. Chem. Soc. 2001, 123: 6439

Google Scholar
5d Mattson AE. Zuhl AM. Reynolds TE. Scheidt KA. J. Am. Chem. Soc. 2006, 128: 4932

Google Scholar
6a Albanese D. Landini D. Penso M. J. Org. Chem. 1998, 63: 9587

Google Scholar
6b Shellhamer DF. Horney MJ. Pettus BJ. Pettus TL. Stringer JM. Heasley VL. Syvert RG. Dobrolsky JM. J. Org. Chem. 1999, 64: 1094

Google Scholar
6c Fan R.-H. Zhou Y.-G. Zhang W.-X. Hou X.-L. Dai L.-X. J. Org. Chem. 2004, 69: 335

Google Scholar
6d Yin J. Zarkowsky DS. Thomas DW. Zhao MM. Huffman MA. Org. Lett. 2004, 6: 1465

Google Scholar
6e Sun H. DiMagno SG. J. Am. Chem. Soc. 2005, 127: 2050

Google Scholar
7a Clark JH. Chem. Rev. 1980, 80: 429

Google Scholar
7b Pearson AJ. Roush WR. Activating Agents and Protecting Groups J. Wiley and Sons; Chichester: 1999.

Google Scholar
7c Ooi T. Maruoka K. Acc. Chem. Res. 2004, 37: 526

Google Scholar
7d Ménand M. Dalla V. Synlett 2005, 95

Google Scholar
8 Poupelin JP. Saint-Ruf G. Foussard-Blanpin O. Marcisse G. Uchida-Ernouf G. Lacroix R. Eur. J. Med. Chem. 1978, 67

Google Scholar
9 Lambert RW, Martin JA, Merrett JH, Parkes KEB, and Thomas GJ. inventors; WO 9706178.
10 Hideo T, and Teruomi J. inventors; JP 56005480.
11a Banerjee A. Mukherjee AK. Stain Technol. 1981, 56: 83

Google Scholar
11b Menchen SM, Benson SC, Lam JYL, Zhen W, Sun D, Rosenblum BB, Khan SH, and Taing M. inventors; US 6583168.
12 Knight CG. Stephens T. Biochem. J. 1989, 258: 683

Crossref Google Scholar

13

Analytical Data of Compounds 4 and 69,9-Dimethyl-12-phenyl-8,9,10,12-tetrahydro-benzo[ a ]-xanthen-11-one (4a)
White solid; mp 152-153 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.98 (d, J = 8.4 Hz, 1 H), 7.78-7.73 (m, 2H), 7.44-7.40 (m, 1H), 7.37-7.30 (m, 4 H), 7.16 (t, J = 7.6 Hz, 2 H), 7.04 (t, J = 7.3 Hz, 1 H), 5.71 (s, 1 H), 2.56 (s, 2 H), 2.30 (d, J = 16.3 Hz, 1 H), 2.23 (d, J = 16.3 Hz, 1 H), 1.11 (s, 3 H), 0.95 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.03, 164.07, 147.95, 144.94, 131.69, 131.61, 129.01, 128.62, 128.57, 128.42, 127.19, 126.42, 128.05, 123.88, 117.91, 117.23, 114.48, 51.11, 41.62, 34.90, 32.45, 29.48, 27.36. HRMS (EI): m/z calcd. for C₂₅H₂₂O₂ [M⁺]: 354.1620; found: 354.1621. 12-(4-Fluorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-benzo[ a ]xanthen-11-one (4b) White solid; mp 185-186 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.92 (d, J = 8.4 Hz, 1 H), 7.78-7.74 (m, 2 H), 7.44-7.40 (m, 1 H), 7.38-7.34 (m, 1 H), 7.32-7.23 (m, 3 H), 6.84 (t, J = 8.7 Hz, 2 H), 5.69 (s, 1 H), 2.54 (s, 2 H), 2.30 (d, J = 16.3 Hz, 1 H), 2.23 (d, J = 16.3 Hz, 1 H), 1.10 (s, 3 H), 0.94 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.06, 164.09, 161.38 (d, J = 254 Hz), 147.93, 140.75 (d, J = 3 Hz), 131.71, 131.44, 130.08 (d, J = 8 Hz), 129.19, 128.65, 127.24, 125.16, 123.71, 117.56, 117.23, 115.22 (d, J = 21 Hz), 114.28, 51.06, 41.56, 34.17, 32.42, 29.49, 27.25. HRMS (EI): m/z calcd for C₂₅H₂₁FO₂ [M⁺]: 372.1526; found: 372.1528. 12-(4-Chlorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-benzo[ a ]xanthen-11-one (4c) White solid; 182-183 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.90 (d, J = 8.2 Hz, 1 H), 7.79 (d, J = 6.1 Hz, 1 H), 7.77 (d, J = 8.4 Hz, 1 H), 7.45-7.42 (m, 1 H), 7.40-7.36 (m, 1 H), 7.32 (d, J = 8.9 Hz, 1 H), 7.25 (s, 2 H), 7.13 (d, J = 8.4 Hz, 2 H), 2.56 (s, 2 H) 2.31 (d, J = 16.3 Hz, 1 H), 2.24 (d, J = 16.3 Hz, 1 H), 1.12 (s, 3 H), 0.96 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.07, 164.26, 147.96, 143.46, 132.14, 131.74, 131.44, 130.01, 129.31, 128.70, 128.61, 127.33, 125.24, 123.68, 117.29, 117.25, 114.05, 51.08, 41.62, 34.40, 32.47, 29.51, 27.35. HRMS (EI): m/z calcd for C₂₅H₂₁ClO₂ [M⁺]: 388.1230; found: 388.1227. 9,9-Dimethyl-12-(4-nitrophenyl)-8,9,10,12-tetrahydro-benzo[ a ]xanthen-11-one (4d) White solid; mp 183-185 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 8.03 (d, J = 8.7 Hz, 2 H), 7.84-7.80 (m, 3 H), 7.51 (d, J = 8.7 Hz, 2 H), 7.44-7.37 (m, 2 H), 7.36 (d, J = 9.0 Hz, 1 H), 2.60 (s, 2 H), 2.33 (d, J = 16.3 Hz, 1 H), 2.24 (d, J = 16.3 Hz, 1 H), 1.13 (s, 3 H), 0.95 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 196.92, 164.82, 152.07, 148.00, 146.57, 131.79, 131.24, 129.84, 129.56, 128.87, 127.59, 125.45, 123.83, 123.32, 117.29, 116.25, 113.21, 51.00, 41.64, 35.08, 32.47, 29.49, 27.28. HRMS (EI): m/z calcd for C₂₅H₂₁NO₄ [M⁺]: 399.1471; found: 399.1471. 12-(4-Hydroxyphenyl)-9,9-dimethyl-8,9,10,12-tetra-hydrobenzo[ a ]xanthen-11-one (4e) White solid; mp 213-214 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.97 (d, J = 8.3 Hz, 1 H), 7.77-7.72 (m, 2 H), 7.40 (t, J = 8.0 Hz, 1 H), 7.35 (t, J = 7.3 Hz, 1 H), 7.30 (d, J = 8.9 Hz, 1 H), 7.14 (d, J = 8.4 Hz, 2 H), 6.73 (s, 1 H), 6.58 (d, J = 8.4 Hz, 2 H), 5.61 (s, 1 H), 2.54 (s, 2 H), 2.30 (d, J = 16.4 Hz, 1 H), 2.24 (d, J = 16.4 Hz, 1 H), 1.08 (s, 3 H), 0.94 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 198.41, 164.73, 154.68, 147.75, 136.72, 131.73, 131.57, 129.70, 128.94, 128.56, 127.17, 125.11, 123.98, 118.07, 117.17, 115.55, 114.70, 51.03, 41.61, 34.12, 32.55, 29.38, 27.32. HRMS (EI): m/z calcd for C₂₅H₂₂O₃ [M⁺]: 370.1569; found: 370.1570. 12-(4-Methoxyphenyl)-9,9-dimethyl-8,9,10,12-tetra-hydrobenzo[ a ]xanthen-11-one (4f) White solid; mp 211-212 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.98 (d, J = 8.4 Hz, 1 H), 7.74 (t, J = 9.3 Hz, 2 H), 7.42 (t, J = 7.4 Hz, 1 H), 7.35 (t, J = 7.3 Hz, 1 H), 7.30 (d, J = 8.9 Hz, 1 H), 7.24 (d, J = 8.6 Hz, 2 H), 6.69 (d, J = 8.6 Hz, 2 H), 5.65 (s, 1 H), 3.66 (s, 3 H), 2.54 (s, 2 H), 2.29 (d, J = 16.4 Hz, 1 H), 2.23 (d, J = 16.4 Hz, 1 H), 1.10 (s, 3 H), 0.96 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.11, 163.81, 157.96, 147.86, 137.34, 131.66, 129.52, 128.87, 128.54, 127.10, 125.01, 123.85, 118.06, 117.20, 114.58, 113.75, 55.21, 51.08, 41.54, 33.99, 32.40, 29.45, 27.34. HRMS (EI): m/z calcd for C₂₆H₂₄O₃ [M⁺]: 384.1725; found: 384.1726. 12-[Benzo[ d ][1,3]dioxol-5-yl}-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[ a ]xanthen-11-one (4g) White solid; mp 213-214 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.98 (d, J = 8.4 Hz, 1 H), 7.78 (d, J = 8.5 Hz, 1 H), 7.75 (d, J = 9.0 Hz, 1 H), 7.44 (td, J = 7.0, 1.2 Hz, 1 H), 7.38 (td, J = 7.9, 0.9 Hz, 1 H), 7.30 (d, J = 8.9 Hz, 1 H), 6.85 (dd, J = 8.0, 1.7 Hz, 1 H), 6.78 (d, J = 1.6 Hz, 1 H) 6.61 (d, J = 8.0 Hz, 1 H), 5.81 (dd, J = 16.9, 1.3 Hz, 1 H), 5.63 (s, 1 H), 2.56 (s, 2 H), 2.31 (d, J = 16.4 Hz, 1 H), 2.26 (d, J = 16.4 Hz, 1 H), 1.11 (s, 3 H), 0.99 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.12, 163.98, 147.93, 147.69, 146.00, 139.12, 131.72, 131.60, 129.05, 128.62, 127.20, 125.13, 123.88, 121.96, 117.90, 117.27, 114.48, 109.17, 108.12, 100.95, 51.17, 41.63, 34.52, 32.47. HRMS (EI): m/z calcd for C₂₆H₂₂O₄ [M⁺]: 398.1518; found: 398.1506. 12-(1 H -indol-3-yl)-9,9-dimethyl-8,9,10,12-tetrahydro-benzo[ a ]xanthen-11-one (4h) Colorless oil. ^¹H NMR (400 MHz, CDCl₃): δ = 8.13 (d, J = 8.4 Hz, 1 H), 7.99 (s, 1 H), 7.73-7.71 (m, 2 H), 7.53 (d, J = 8.0 Hz, 1 H), 7.37-7.29 (m, 3 H), 7.20 (dd, J = 5.2, 2.8 Hz, 2 H), 7.03 (td, J = 7.1, 0.7 Hz, 1 H), 6.95 (td, J = 7.5, 0.8 Hz, 1 H), 6.01 (s, 1 H), 2.62 (d, J = 17.2 Hz, 1 H), 2.56 (d, J = 17.2 Hz, 1 H), 2.28 (d, J = 16.0 Hz, 1 H), 2.21 (d, J = 16.0 Hz, 1 H), 1.10 (s, 3 H), 0.90 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.52, 163.96, 147.78, 136.54, 132.02, 131.71, 128.83, 128.53, 126.91, 126.19, 124.92, 123.89, 123.58, 121.68, 119.59, 119.58, 117.63, 117.14, 113.64, 111.24, 51.22, 41.59, 32.46, 29.28, 27.75, 26.78. 12-Butyl-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[ a ]-xanthen-11-one (4i) White solid; mp 120-122 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 8.10 (d, J = 8.4 Hz, 1 H), 7.81 (d, J = 8.0 Hz, 1 H), 7.69 (d, J = 8.8 Hz, 1 H), 7.53 (t, J = 7.7 Hz, 1 H), 7.42 (t, J = 7.8 Hz, 1 H), 7.19 (d, J = 8.9 Hz, 1 H), 4.72 (t, J = 4.5 Hz, 1 H), 2.56 (d, J = 17.6 Hz, 1 H), 2.50 (d, J = 17.6 Hz, 1 H), 2.38 (d, J = 16.4 Hz, 1 H), 2.32 (d, J = 16.4 Hz, 1 H), 1.81-1.75 (m, 2 H), 1.19 (s, 3 H), 1.14 (s, 3 H), 1.14-1.04 (m, 3 H), 0.89-0.82 (m, 1 H), 0.71 (t, J = 7.1 Hz, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.72, 166.28, 148.68, 131.63, 131.44, 128.74, 128.14, 126.89, 124.97, 123.44, 118.62, 117.01, 113.02, 51.26, 41.59, 35.00, 32.34, 29.86, 28.14, 27.48, 27.29, 22.93, 14.21. HRMS (EI): m/z calcd for C₂₃H₂₆O₂ [M⁺]: 334.1933; found: 334.1927. 9,9-Dimethyl-12-(naphthalen-2-yl)- 8,9,10,12-tetra-hydrobenzo[ a ]xanthen-11-one (4j) White solid; mp 231-233 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 8.04 (d, J = 8.4 Hz, 1 H), 7.81 (s, 1 H), 7.80-7.71 (m, 3 H), 7.67 (d, J = 7.7 Hz, 1 H), 7.64 (d, J = 8.8 Hz, 1 H), 7.46 (d, J = 8.4 Hz, 1 H), 7.42-7.29 (m, 5 H), 5.88 (s, 1 H), 2.58 (s, 2 H), 2.25 (q, J = 16.1 Hz, 2 H), 1.10 (s, 3 H), 0.92 (s, 3 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.08, 164.16, 148.04, 142.32, 133.51, 132.34, 131.74, 131.67, 129.16, 128.58, 128.22, 128.21, 127.62, 127.34, 127.23, 126.92, 125.91, 125.60, 125.11, 123.91, 117.76, 117.27, 114.27, 51.11, 41.66, 35.11, 32.44, 29.49, 27.41. 12-(4-Hydroxyphenyl)-8,9,10,12-tetrahydrobenzo[ a ]-xanthen-11-one (4k) White solid; mp 293-296 ˚C. ^¹H NMR (400 MHz, DMSO-d ₆): δ = 9.17 (s, 3 H), 7.99 (d, J = 8.4 Hz, 1 H), 7.90 (d, J = 7.4 Hz, 1 H), 7.89 (d, J = 8.9 Hz, 1 H), 7.48 (td, J = 7.0, 1.1 Hz, 1 H), 7.44-7.39 (m, 2 H), 7.05 (d, J = 8.5 Hz, 2 H), 6.55 (d, J = 8.5 Hz, 2 H), 5.48 (s, 1 H), 2.77-2.70 (m, 2 H), 2.41-2.27 (m, 2 H), 2.02-1.96 (m, 1 H), 1.90-1.79 (m, 1 H). ^¹³C NMR (100 MHz, DMSO-d ₆): δ = 196.18, 165.27, 155.56, 147.11, 135.70, 131.02, 130.65, 129.03, 128.76, 128.47, 126.99, 124.84, 123.29, 117.76, 117.07, 114.88, 114.82, 36.49, 33.06, 26.89, 19.97. HRMS (EI): m/z calcd for C₂₃H₁₈O₃ [M⁺]: 342.1256; found: 342.1257. 12-(4-Nitrophenyl)-8,9,10,12-tetrahydrobenzo[ a ]-xanthen-11-one (4l) White solid; mp 246-247 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 8.03 (d, J = 8.7 Hz, 2 H), 7.82-7.79 (m, 3 H), 7.50 (d, J = 8.7 Hz, 2 H), 7.45-7.35 (m, 3 H), 2.79-2.70 (m, 2 H), 2.48-2.36 (m, 2 H), 2.11-2.05 (m, 1 H), 2.00-1.93 (m, 1 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 197.08, 166.50, 152.31, 147.97, 146.55, 131.77, 131.20, 129.82, 129.62, 128.84, 127.56, 125.42, 123.84, 123.33, 117.22, 116.24, 114.45, 37.13, 35.02, 27.96, 20.42. HRMS (EI): m/z calcd for C₂₃H₁₇NO₄ [M⁺]: 371.1158; found: 371.1156. 1-Phenyl-1 H -benzo[ f ]chromen-3 (2 H )-one (6a) White solid; mp 117-118 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.85 (d, J = 9.2 Hz, 2 H), 7.78 (d, J = 8.1 Hz, 1 H), 7.48-7.40 (m, 2 H), 7.34 (d, J = 8.9 Hz, 1 H), 7.26-7.17 (m, 3 H), 7.11 (d, J = 7.1 Hz, 2 H), 4.94 (dd, J = 6.4, 2.2 Hz, 1 H), 3.22-3.12 (m, 2 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 167.26, 149.99, 140.74, 131.28, 131.19, 130.11, 129.41, 128.94, 127.76, 127.65, 127.12, 125.44, 123.24, 117.79, 117.74, 37.84, 37.65. HRMS (EI): m/z calcd. for C₁₉H₁₄O₂ [M⁺]: 274.0994; found: 274.0986. 1-(4-Fluorophenyl)-1 H -benzo[ f ]chromen-3 (2 H )-one (6b) White solid; mp 138-139 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.88 (d, J = 9.2 Hz, 1 H), 7.87 (d, J = 9.2 Hz, 1 H), 7.75 (d, J = 8.2 Hz, 1 H), 7.51-7.43 (m, 2 H), 7.35 (d, J = 8.9 Hz, 1 H), 7.11-7.06 (m, 2 H), 6.98-6.92 (m, 2 H), 3.21 (dd, J = 15.8, 3.2 Hz, 1 H), 3.13 (dd, J = 15.8, 2.1 Hz, 1 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 167.07, 163.53, 161.08, 149.99, 136.45, 136.41, 131.35, 131.07, 130.34, 129.06, 128.86, 128.78, 127.79, 125.57, 123.08, 117.79, 117.61, 116.47, 116.25, 37.77, 37.14. HRMS (EI): m/z calcd for C₁₉H₁₃FO₂ [M⁺]: 292.0900; found: 292.0901. 1-(4-Chlorophenyl)-1 H -benzo[ f ]chromen-3 (2 H )-one (6c) Colorless oil. ^¹H NMR (400 MHz, CDCl₃): δ = 7.91-7.83 (m, 2 H), 7.73 (d, J = 8.1 Hz, 1 H), 7.52-7.41 (m, 2 H), 7.34 (d, J = 9.2 Hz, 1 H), 7.23 (d, J = 8.4 Hz, 2 H), 7.05 (d, J = 8.4 Hz, 2 H), 4.93 (d, J = 6.2 Hz, 1 H), 3.22 (dd, J = 15.7 Hz,
1 H), 3.12 (dd, J = 15.7 Hz, 1 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 166.94, 150.03, 139.20, 133.72, 131.04, 130.42, 129.63, 129.07, 128.59, 127.83, 125.61, 123.02, 117.78, 117.26, 37.55, 37.26. 1-(4-Methoxyphenyl)-1 H -benzo[ f ]chromen-3 (2 H )-one (6d) White solid; mp 132-133 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.85 (d, J = 8.7 Hz, 2 H), 7.78 (d, J = 8.2 Hz, 1 H), 7.48-7.40 (m, 2 H), 7.33 (d, J = 8.9 Hz, 1 H), 7.02 (d, J = 8.6 Hz, 2 H), 6.77 (d, J = 8.7 Hz, 2 H), 4.90 (dd, J = 6.2, 2.2 Hz, 1 H), 3.71 (s, 3 H), 3.17 (dd, J = 15.8, 6.4 Hz, 1 H), 3.11 (dd, J = 15.8, 2.6 Hz, 1 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 167.34, 158.92, 149.70, 132.61, 131.11, 131.02, 129.84, 128.78, 128.04, 127.74, 127.48, 125.29, 123.14, 118.10, 117.55, 114.60, 114.36, 55.20, 37.63, 36.80. 1-(Naphthalen-2-yl)-1 H -benzo[ f ]chromen-3 (2 H )-one (6e) White solid; mp 178-180 ˚C. ^¹H NMR (400 MHz, CDCl₃): δ = 7.90 (d, J = 9.0 Hz, 1 H), 7.89-7.84 (m, 1 H), 7.82-7.74 (m, 3 H), 7.65-7.63 (m, 1 H), 7.45-7.37 (m, 6 H), 7.33 (dd, J = 8.5, 1.6 Hz, 1 H), 5.10 (dd, J = 5.9, 3.0 Hz, 1 H), 3.30-3.21 (m, 2 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 167.21, 150.13, 138.15, 133.70, 132.90, 131.35, 131.26, 130.26, 129.49, 128.98, 128.08, 127.80, 127.70, 126.55, 126.29, 125.93, 125.49, 125.20, 123.28, 117.82, 117.66, 38.06, 37.61.