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Synlett
Volumn , Issue 12, 2009, Pages 1937-1940
Platinum- and palladium-catalyzed sequential reactions: Regioselective synthesis of 9-fluorenylidenes from 9-ethynylfluoren-9-yl carboxylates and furans
Author keywords

Carbene; Fluorene; Palladium; Platinum; Ring opening
Indexed keywords

CARBOXYLIC ACID DERIVATIVE; FLUORENE DERIVATIVE; FURAN DERIVATIVE; PALLADIUM; PLATINUM;
EID: 67651247357     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0029-1217531     Document Type: Article
Times cited : (7)
References (30)
  • 16
    • 48749097043 scopus 로고    scopus 로고
    • For selected examples, see: a
    • For selected examples, see: (a) Dahl, B. J.; Mills, N. S. J. Am. Chem. Soc. 2008, 130, 10179.
    • (2008) J. Am. Chem. Soc , vol.130 , pp. 10179
    • Dahl, B.J.1    Mills, N.S.2
  • 21
    • 67651231944 scopus 로고    scopus 로고
    • General Procedure of Ring-Opening Reaction of 2-Methylfuran In a flame-dried Schlenk tube, PtCl2 (6.5 mg, 0.025 mmol, 5 mol, was dispersed in toluene (2.0 mL, To the solution were added 1a (124 mg, 0.50 mmol) and 2-methylfuran (90 μL, 1.0 mmol) at r.t. The mixture was stirred at 50°C for 7 h. The yellow suspension was cooled and the solvent was removed under reduced pressure to give 2a. To remove the platinum catalyst, the crude 2a was dissolved in THF (30 mL) and the solution was passed through a short Florisil column. The THF solution was evaporated under reduced pressure to give 2a (99, Z,Z/Z,E, 63:37, In the case of [RuCl2(CO)3]2, the THF solution obtained after a Florisil column was evaporated in vacuo, and the residue was purified by centrifuge with hexane and a small amount of THF to give a first crop of (E,E)-2a ca. 65% yield, The hexane and THF solution cont
    • 2 with hexane-EtOAc (v/v = 4:1) to give a second crop of (E,E)-2a (ca. 10% yield). The yield in Scheme 2 was obtained by combining first and second crops of (E,E)-2a.
  • 22
    • 67651221537 scopus 로고    scopus 로고
    • Analytical Data of (E,E)-2a, Z,Z)-2a and (Z,E)-2a Compound (E,E)-2a: yield 74, a yellow solid; mp 203.7-204.1 °C. IR (KBr, 3054, 1752 (C=O, 1654, 1198, 1176, 728 cm-1. 1H NMR (400 MHz, CDCl3, δ, 2.34 (s, 3 H, 2.51 (s, 3 H, 6.32 (d, J, 15.2 Hz, 1 H, 6.63 (dd, J, 11.2, 14.6 Hz, 1 H, 7.25-7.34 (m, 5 H, 7.63 (d, J, 14.6 Hz, 1 H, 7.68 (d, J, 8.0 Hz, 1 H, 7.70 (d, J, 8.0 Hz, 1 H, 7.77 (d, J, 8.0 Hz, 1 H, 7.79 (d, J, 8.0 Hz, 1 H, 13C NMR (100 MHz, CDCl3, δ, 21.1, 27.6, 119.9, 120.2, 125.2, 125.3, 127.3, 127.7, 128.8, 129.2, 130.8, 131.1, 132.3, 132.7, 135.6, 136.7, 140.3, 140.9, 141.6, 144.8, 168.2, 198.0. Anal. Calcd for C 22H18O3: C, 79.98, H, 5.49. Found: C, 79.87; H, 5.66. Compounds (Z,Z)-2a and (Z,E)-2a: yield 99, a
    • 3): δ = 21.1, 21.2, 31.9, 31.9, 119.8, 119.8, 120.0, 125.0, 125.1, 125.1, 125.4, 126.6, 127.1, 127.1, 127.4, 127.6, 127.7, 128.4, 128.5, 128.7, 128.9, 129.0, 130.2, 130.5, 130.8, 132.9, 135.7, 135.7, 136.4, 136.5, 136.8, 140.0, 140.1, 140.3, 140.7, 140.8, 144.0, 145.6, 167.7, 168.4, 198.5, 198.6 (two carbon peaks could not be distinguished with other aromatic carbons).
  • 23
    • 67651223616 scopus 로고    scopus 로고
    • 9b Although we cannot explain the difference at present, we presume that the reaction of 1a using the ruthenium catalyst would proceed via a completely different pathway.
    • 9b Although we cannot explain the difference at present, we presume that the reaction of 1a using the ruthenium catalyst would proceed via a completely different pathway.
  • 26
    • 67651223615 scopus 로고    scopus 로고
    • 2 was purchased from Wako Pure Chemicals Inc. (Japan) and used without further purification.
    • 2 was purchased from Wako Pure Chemicals Inc. (Japan) and used without further purification.
  • 27
    • 67651239953 scopus 로고    scopus 로고
    • 2, no (E,E)-2a was detected, and 1a was recovered in 70% yield.
    • 2, no (E,E)-2a was detected, and 1a was recovered in 70% yield.
  • 28
    • 67651213196 scopus 로고    scopus 로고
    • Although THF is one of the suitable solvents for the isomerization reaction of 2a, the reaction of 1a and 2-methylfuran with PtCl2/PdCl2 in THF gave (E,E)-2a selectively but in a lower yield than that in toluene because of unidentified byproduct formation
    • 2 in THF gave (E,E)-2a selectively but in a lower yield than that in toluene because of unidentified byproduct formation.
  • 29
    • 67651206929 scopus 로고    scopus 로고
    • Since the reaction using [RuCl2 (CO)3]2 gave (E,E)-2a regioselectively, as shown in Scheme 2, we also examined co-catalytic system using [RuCl2 (CO)3] 2 and PtCl2. When the reaction of 1a with 2-methylfuran (2 equiv) in 5 mol% of PtCl2 and 5 mol% of [RuCl 2(CO)3]2 was carried out at 50°C, we obtained 2a with a mixture of three regioisomers (Z,Z/Z,E/ E,E, 27:28:45) in 93% yield. This indicates that the ruthenium complex has comparatively lower catalytic activity for isomerization reaction than palladium compounds shown in Table 1
    • 2 was carried out at 50°C, we obtained 2a with a mixture of three regioisomers (Z,Z/Z,E/ E,E = 27:28:45) in 93% yield. This indicates that the ruthenium complex has comparatively lower catalytic activity for isomerization reaction than palladium compounds shown in Table 1.
  • 30
    • 67651220456 scopus 로고    scopus 로고
    • General Procedure of Ring-Opening Reaction and Sequential Isomerization Reaction In a flame-dried Schlenk tube, PtCl2 (1.3 mg, 0.0050 mmol) and PdCl2 (0.9 mg, 0.0050 mmol) were dispersed in toluene (4.0 mL, To this solution were added 1a (124 mg, 0.50 mmol) and 2-methylfuran (50 μL, 0.55 mmol) at r.t. The mixture was stirred at 50°C for 7 h. The yellow suspension was cooled, and the solvent was removed under reduced pressure to give 2a. To remove the transition-metal catalysts, the crude 2a was dissolved in THF (30 mL, and the solution was passed through a short Florisil column. The THF solution was evaporated under reduced pressure to give (E,E)-2a in 99% yield. For reactions using other furans, the THF solution obtained after a Florisil column was evaporated in vacuo, and the residue was purified by centrifuge with hexane and a small amount of THF to give a first crop of (E,E)-2. The hexane and THF
    • 2 with hexane-EtOAc (v/v = 4:1) to give a second crop of (E,E)-2. The yield in Table 2 was obtained by combining first and second crops of (E,E)-2. The analytical data of (E,E)-2 are summarized in the Supporting Information.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.