Synthese von einigen 2H‐Pyran‐2‐on‐Derivaten

Abstract

Derivatives of 6-unsubstituted 2H-pyran-2-one have been synthesized by several different methods. The 4-chloro-2H-pyran-2-one (9) is the most important, since it serves as starting material for the synthesis of different 4-substituted 2H-pyran-2-ones (Scheme 2). Also described are simple transformations of cumalic-acid derivatives producing 5-(2,2-dichlorovinyl)-2H-pyran-2-one (23), 2-0~0-2H-pyran-2-carbonitrile (26), and 4,5-bis(tritluoromethyl)-2H-pyran-2-one (32) (Scheme 3 and 4 ) .

Selective Cyclodimerization and Cyclotrimerization of Acetals Bearing Electron‐Withdrawing Groups Catalyzed by Lewis Acids

“…Heteropolyacid (H 4 PMo 11 VO 40 ·13H 2 O) was prepared according to a literature procedure. [13] Compounds 2, [6] 3, [7] 6a, [14] and 7 [10a] were reported previously.…”

“…[5] Kvita reported an alternative method for preparing ethyl coumalate through Claisen condensation of diethyl 2-pentadioate followed by cyclization under the influence of formic acid. [6] However, the yields of the desired compounds by these methods were moderate. Therefore, the development of a new versatile route to coumalic acids from readily available compounds seems to be interesting.…”

Studies towards Trichodimerol: Novel Cascade Reactions and Polycyclic Frameworks

“…The residue was purified by flash chromatography (silica gel, hexanes: ethyl acetate 2:1) to afford endione 44 (7.2 mg, 0.020 mmol, 24 %, 47 % based on recoverd starting material) as a white crystalline solid. R f 0.28 (silica gel, hexanes:ethyl acetate 2:1); IR (thin film): n Ä max (cm À1 ) 2960 w (CÀH), 1746 s (CO, lactone), 1716 s (CO, ketone), 1692 s (CO, enone), 1257 s, 1162 m, 1124 s, 1084 s, 1055 m, 922 s, 848 s; 1 H NMR (500 MHz, CDCl 3 ): d 6.87 (d, 3 J 1,2 10 Hz, 1 H, Pos 1), 6.01 (dd, 3 J 2,1 10 Hz, 4 J 2,4a 1 Hz, 1 H, Pos 2), 2.97 (dd, 2 J 4a,4b 16 Hz, 4 J 4a,2 1 Hz, 1 H, Pos 4a), 2.77 (d, 2 J 4b,4a 16 Hz, 1 H, Pos 4b), 2.48 (ddd, 2 J 9a,9b 18 Hz, 3 J 9a,8a 9.5 Hz, 3 J 9a,8b 6.5 Hz, 1 H, Pos 9a), 2.35 (ddd, 2 J 9b,9a 18 Hz, 3 J 9b,8b 9 Hz, 3 J 9b,8a 2 equiv) in THF (0.3 mL) at À 78 8C. The temperature was slowly raised to À 50 8C over 1 h. Then mCPBA (50 mg, 57 ± 86 % wt, % 0.15 mmol, % 5 equiv) was added in one batch and the temperature was raised within the next 1 h to 0 8C.…”

“…H NMR (600 MHz, CDCl 3 ): d 6.90 (s, 1 H, Pos 1) 6.57 (d,3 J 8,916 Hz, 1 H, Pos 8),6.04 (d,3 J 9,816 Hz, 1 H, Pos 9), 3.25 (d, 2 J 4a,4b16 Hz, 1 H, Pos 4a), 2.91 (d, 2 J 4b,4a16 Hz, 1 H, Pos 4b), 2.22 (s, 3 H, Pos 11), 1.66 (s, 3 H, CH 3 ), 1.64 (s, 3 H, CH 3 ), 0.28 (s, 9 H, Si(CH 3 ) 3 );13 C NMR (150 MHz, CDCl 3 ): d 197.7 (Pos 10), 187.0 (Pos 3), 168.4 (Pos 12), 145.3/144.8 (Pos 1 Pos 8), 132.9 (Pos 2), 130.4 (Pos 9), 97.1 (Pos 5), 85.3/77.6 (Pos 6 Pos 13), 48.4 (Pos 4), 29.4, 29.2, 24.5, 2.6; HRMS: calcd for C 17 H 23 O 6 SiCl ([M H ]) 387.1031, found 387.1024. [2 2] Adduct 47 b: A degassed solution of diendione 42 (10.0 mg, 0.028 mmol) in [D 6 ]benzene (0.4 mL) in an NMR tube was irradiated for 30 min with a mercury medium-pressure lamp (see General techniques section).…”

Über die Reaktion einiger 2H‐Pyran‐2‐on‐Derivate mit primären Aminen

“…: C 69,99,H 7,34,N 4,24. Nuchweis 5,19 (d, J = 12,8, H-C(2)); 3,64 (s, MeO); 3,29, 1,55,1,32,0,91 (BUN). "C-NMR ((D,)DMSO): 168,5 (d, J = 13,7,COO); 168,l (br., COOMe); 158,3 (d, J = 166, NC = C(4)); 141, 8 (dd, J = 149,9, 3,6, C(3)); 106,2 (d, J = 159,2, C(2)); 91,3 (d, J = 9,3, C(4)); 50,3 (q,J = 146,4,MeO);48,3,32,3,18,9,13,4 (BUN).…”