Synlett 2016; 27(09): 1367-1370
DOI: 10.1055/s-0035-1561389
letter
© Georg Thieme Verlag Stuttgart · New York

GaCl3-Mediated Isomerization of Donor–Acceptor Cyclopropanes into (2-Arylalkylidene)malonates

Roman A. Novikov
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prosp., 119991 Moscow, Russian Federation   Email: tom@ioc.ac.ru
,
Anna V. Tarasova
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prosp., 119991 Moscow, Russian Federation   Email: tom@ioc.ac.ru
,
Yury V. Tomilov*
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prosp., 119991 Moscow, Russian Federation   Email: tom@ioc.ac.ru
› Author Affiliations
Further Information

Publication History

Received: 18 November 2015

Accepted after revision: 19 January 2016

Publication Date:
01 March 2016 (online)


Abstract

A new process for isomerization of donor–acceptor cyclopropanes (2-arylcyclopropanedicarboxylates) by treatment with anhydrous gallium trichloride to give (2-arylalkylidene)malonates in high yields and with good selectivity has been developed. The reaction involves initial formation of a 1,2-dipolar gallium complex.

Supporting Information

 
  • References and Notes

  • 6 Novikov RA, Balakirev DO, Timofeev VP, Tomilov YV. Organometallics 2012; 31: 8627
  • 8 General Procedure for the Synthesis of (2-Arylalkylidene)malonates 3a–l All operations were performed in dry argon atmosphere. To a solution of cyclopropane 1al (0.6 mmol) in dry CH2Cl2 (5 mL) was added the solid GaCl3 (0.66 mmol, 1.1 equiv) in one portion at 0 °C under vigorous stirring. The reaction mixture was stirred at the same temperature during 10–15 min, then MeOH (1.5 mL) was added. After that aqueous solution of HCl (5%) was added at r.t. until pH 2–3 was achieved, and the reaction mixture was extracted with CH2Cl2 (3 × 10 mL). The organic layer was dried over MgSO4, and the solvent was removed in vacuo. The residue was separated by column chromatography on silica gel (eluent: from benzene to benzene–EtOAc, 10:1) to afford target (2-arylalkylidene)malonates 3al as thick colorless oils. If necessary, the obtained products 3al can be additionally purified by second column chromatography on silica gel eluting with hexane to hexane–acetone (10:1). For details, see Table 1 and Supporting Information. Analytical data for representative samples 3c,j,l are provided below. Dimethyl 2-[2-(4-Fluorophenyl)ethylidene]malonate (3c) The title compound was prepared according to the general procedure in 115 mg (76%) yield as a colorless thick oil. IR (CHCl3): ν = 3015, 3008, 2955, 2903, 2848, 1732 (C=O), 1648, 1605, 1511, 1438, 1366, 1264 cm–1. 1H NMR (400.1 MHz, CDCl3): δ = 3.59 (d, 2 H, CH2, 3 J = 7.9 Hz), 3.77 and 3.86 (2 s, 2 × 3 H, 2 CO2Me), 6.95–7.02 (m, 2 H, 2 m-H, 3 J HF = 8.7 Hz), 7.07 (t, 1 H, =CH, 3 J = 7.9 Hz), 7.13–7.20 (m, 2 H, 2 o-H, 4 J HF = 5.3 Hz). 13C NMR (100.6 MHz, CDCl3): δ = 35.1 (CH2), 52.41 and 52.44 (2 OMe), 115.7 (d, 2 m-CH, 2 J CF = 21.5 Hz), 128.3 (=C), 130.3 (d, 2 o-CH, 3 J CF = 8.1 Hz), 132.8 (d, ipso-C, 4 J CF = 3.2 Hz), 147.4 (=CH), 162.0 (d, p-CF, 1 J CF = 245.3 Hz), 164.2 and 165.6 (2 COO). 19F NMR (282.4 MHz, CDCl3): δ = –116.6 (tt, 1F, 3 J HF = 8.7 Hz, 4 J HF = 5.3 Hz). MS: m/z (%) = 252 (2) [M+], 220 (16) [M+ – HOCH3], 188 (21), 133 (100), 109 (36), 83 (24), 59 (93), 29 (24). HRMS: m/z calcd for C13H13O4F: 253.0871 [M + H]+, 275.0690 [M + Na]+; found: 253.0867; 275.0685. Dimethyl 2-[2-(1-Naphthyl)ethylidene]malonate (3j) The title compound was prepared according to the general procedure in 283 mg (98%) yield as a colorless thick oil. IR (CHCl3): ν = 3027, 3011, 2955, 2904, 2848, 1731 (C=O), 1645, 1598, 1511, 1488, 1438, 1396, 1372, 1303, 1268 cm–1. 1H NMR (400.1 MHz, CDCl3): δ = 3.76 and 3.92 (2 s, 2 × 3 H, 2 CO2Me), 4.12 (d, 2 H, CH2, 3 J = 7.5 Hz), 7.23 (t, 1 H, =CH, 3 J = 7.5 Hz), 7.36 (br d, 1 H, H2′ or H4′, 3 J = 7.1 Hz), 7.42 (dd, 1 H, H3′, 3 J = 7.1 and 8.1 Hz), 7.48–7.53 (m, 1 H, H6′ or H7′), 7.53–7.58 (m, 1 H, H6′ or H7′), 7.78 (br d, 1 H, H2′ or H4′, 3 J = 8.1 Hz), 7.86–7.90 (m, 1 H, H5′ or H8′), 7.96–8.01 (m, 1 H, H5′ or H8′). 13C NMR (100.6 MHz, CDCl3): δ = 33.2 (CH2), 52.42 and 52.45 (2 OMe), 123.5, 125.7, 125.9, 126.5, 126.9, 127.9 and 128.9 [7 CH(Ar)], 128.2 (=C), 131.8, 133.6 and 134.0 [3 C(Ar)], 148.4 (=CH), 164.3 and 165.8 (2 COO). MS: m/z (%) = 284 (11) [M+], 252 (28) [M+ – HOCH3], 220 (57), 209 (25), 192 (18), 165 (100), 152 (29), 141 (15), 115 (29), 84 (76), 75 (12), 59 (27), 47 (41), 35 (36). HRMS: m/z calcd for C17H16O4: 307.0941 [M + Na]+; found: 307.0942. Dimethyl 2-[3,4-Dihydronaphthalen-2(1H)-ylidene]malonate (3l) The title compound was prepared according to the general procedure in 116 mg (75%) yield as a colorless thick oil. IR (CHCl3): ν = 3012, 2954, 2905, 2846, 1730 (C=O), 1629, 1493, 1455, 1436, 1349, 1331, 1295, 1262, 1243 cm–1. 1H NMR (400.1 MHz, CDCl3): δ = 2.72–2.85 (m, 4 H, CH2CH2), 3.74 and 3.77 (2 s, 2 × 3 H, 2 CO2Me), 3.87 (br s, 2 H, CH2), 7.03–7.15 [m, 4 H, 4 H(Ar)]. 13C NMR (100.6 MHz, CDCl3): δ = 28.8 and 30.2 (CH2CH2), 35.2 (CH2), 52.0 (2 OMe), 122.5 (=C), 126.4, 126.6, 127.4 and 128.1 [4 CH(Ar)], 134.1 and 137.2 [2 C(Ar)], 159.2 (=C), 165.6 and 165.9 (2 COO). MS: m/z (%) = 260 (7) [M+], 228 (45) [M+ – HOCH3], 200 (16), 168 (36), 157 (11), 141 (86), 128 (100), 115 (65), 103 (7), 91 (9), 77 (20), 65 (17), 59 (51), 51 (10), 39 (26). HRMS: m/z calcd for C15H16O4: 261.1121 [M + H]+, 283.0941 [M + Na]+, 299.0680 [M + K]+; Found: 261.1120; 283.0940; 299.0682.