REFERENCES
- Ellis , G. P. , ed. 1977 . The Chemistry of Heterocyclic Compounds Vol. 31 , New York : John Wiley and Sons . For review on chromanones and its derivatives, see
- Rao , A. V.R. , Gaitonde , A. S. , Prakash , K. R.C. and Rao , S. P. 1994 . Tetrahedron Lett. , 35 : 6347 For some recent example, see
- Kelly , S. E. and Vanderplas , B. C. 1991 . J. Org. Chem. , 56 : 1325
- Koch , K. and Biggers , M. S. 1994 . J. Org. Chem. , 59 : 1216
- Baker , D. C. 1995 . Synthesis , : 630
- Kostka , K. , Pastuszko , S. and Porada , M. 1992 . Phosphorus, Sulfur, and Silicon , 71 : 67 Only one chromone derivative was found
- Lee , C.-W. and Oh , D. Y. 1996 . Heterocycles , 43 : 1171
- Lee , C.-W. , Hong , J. E. and Oh , D. Y. 1995 . J. Org. Chem. , 60 : 7027
- Lee , C.-W. , Gil , J. M. and Oh , D. Y. 1997 . Heterocycles , 45 : 943
- General procedure: To a stirred solution of allyl phosphonate (0.178 g, 1 mmol) with THF at −78°C was added dropwise LiHMDS (3 mL, 1.0 M in THF). After 1 h, salicylate (1 mmol) in THF (1 mL) was added dropwise. Stirring was continued at −78°C for 1 h. The reaction mixture was warmed slowly to room temperature and quenched with 3 N sulfuric acid (10 mL). The aqueous phase was extracted with Et2O (20 mL × 3), dried with MgSO4. The solvent was removed under reduced pressure to give the crude mixture, which was flash chromatography (ethyl acetate : hexane 1:1) to give pure product
- Two diastereomers were distinguished from each other principally by the resonances observed for H-2. The H-2 resonance appears at lower field for the cis-compound which is in accord with observations made for similar systems (see ref. [2a], [2b], [2c], [2d]. Representative spectral data for the entry c (from mixture of isomer, *indicates the discernable H-2 resonances); 1H NMR (300 MHz, CDCl3) one isomer δ 1.11 (t, 3H, J = 7.04 Hz), 1.26 (dd, J = 6.62 Hz, J = 1.55 Hz), 2.90 (dd, J H-H = 1.90 Hz, J P-H = 25.17 Hz), 3.92(m, 4H), 5.10 (m, 1H*), 6.78 (m, 2H), 7.29(m,1H), 7.67 (m, 1H); the other isomer δ 0.86 (t, 3H, J = 6.84 Hz), 1.55 (d, 3H, J = 6.65 Hz), 3.14 (dd, 1H, J H-H = 3.63 Hz, J P-H = 24.45 Hz), 3.78 (m, 4H), 4.83 (m, 1H*), 6.78 (m, 2H), 7.29 (m, 1H), 7.67 (m, 1H); HRMS(EI) calcd. 298.0970 obs. 298.0964
- Al-Badri , H. , About-Jaudet , E. , Conbret , J.-C and Collignon , N. 1995 . Synthesis , : 1401 It was reported that 2-formyl-allyl phosphonate was transformed to the 2-methyl-1-formylethenyl phosphonate, isolated as a mixture of E and Z stereoisomers in ratio of 35:65, during the purification process
- Since a mixture of cis, trans and their enols, which are inseparable on chromatography, was conceivable, the mixture of these isomers was converted to the methylated product in order to confirm cyclized products (see below scheme with entry g). Spectral data for compound 4: 1H NMR (200 MHz, CDCl3) δ 1.28 (dt, 6H, JP-H = 17.87, JH-H = 7.1), 1.71 (d, 3H, J = 9.95), 1.76 (s, 3H), 3.54 (m, 1H), 4.22 (m, 4H), 7.18 (m, 2H), 7.36(m, 1H), 8.12 (m, 1H); 13C NMR (50 MHz, CDCl3) δ 16.04(dd, Ja = Jb = 7.2), 18.43, 19.12 (d, J = 4.6), 43.78, 62.18 (dd, Ja = 6.8, Jb = 13.0), 124.59, 127.17, 128.83, 129.69, 133.23, 139.75, 192.93; HRMS (EI) calc. 328.0898, obs. 328.0890. Spectral data for compound 5: 1H NMR (200 MHz, CDCl3) δ 1.34 (t, 6H, J = 6.7), 1.40(m, 3H), 3.67 (S, 3H), 3.92(m, 1H), 4.15 (m, 4H), 7.31 (m, 3H), 7.55(m, 1H); 13C NMR (50 MHz, CDCl3) δ 16.38(d, J = 6.6), 21.50 (d, J = 2.0), 34.71 (d, J = 10.5), 60.57, 61.87 (dd, Ja = 5.6, Jb = 15.1), 113.69 (d, J = 178.9), 125.21 (d, J = 1.35), 125.60, 127.16 (d, J = 11.7), 128.89, 130.08, 134.80, 161.94; HRMS (EI) calc. 3280.898, obs. 328.0906
- Spectral data for the entry d: 1H NMR (200 MHz, CDCl3) δ 0.96 (t, 6H, J = 7.0), 1.46 (t, 3H, J = 4.9), 3.86 (m, 4H), 4.59 (dd, 1H, JP-H = 23.2, JH-H = 7.5), 5.56 (m, 2H), 6.65 (m, 2H), 7.18 (m, 1H), 7.56 (m, 1H), 11.76 (s, 1H). Spectral data for the entry e: 1H NMR (200 MHz, CDCl3) δ 1.25 (t, 6H, J = 7.1), 1.80 (m, 6H), 4.14 (m, 4H), 5.05 (dd, 1H, JP-H = 23.24, JH-H = 9.9), 5.55 (m, 1H), 6.92 (m, 2H), 7.44 (m, 1H), 7.84 (m, 1H), 12.09 (s, 1H); 13C NMR (50 MHz, CDCl3) δ 15.82 (d, J = 5.9), 18.05 (d, J = 2.6), 25.43 (d, J = 3.2), 47.46 (d, J = 132.6), 62.55 (dd, Ja = 2.5, Jb = 7.2), 114.23 (d, J = 11.35), 118.10, 118.49, 118.70 (d, J = 3.3), 130.16, 136.35, 137.67 (d, J = 12.7), 162.63, 199.89 (d, J = 5.2). Spectral data for the entry f: 1H NMR (200 MHz, CDCl3) δ 1.29 (dt, 6H, Ja = 2.3, Jb = 6.7), 4.14 (m, 4H), 5.00 (dd, 1H, JP-H = 24.14, JH-H = 8.28), 6.60 (m, 2H), 6.99 (m, 2H), 7.35 (m, 6H), 7.86 (m, 1H), 12.06 (s, 1H); 13C NMR (50 MHz, CDCl3) δ 16.22 (d, J = 6.0), 51.75 (d, J=130.25), 63.37 (dd, Ja = Jb = 6.4), 118.78 (d, J = 16.4), 119.69 (d, J = 12.4), 126.47 (d, J = 2.0), 128.08, 128.55, 130.71, 135.40 (d, J = 12.8), 136.04 (d, J = 4.0), 136.96, 163.12, 199.52 (d, J = 5.5)