Kondensationsreaktionen mit Ketocarbonsäurederivaten

Abstract

Mono-und Dialkylphenole reagieren unter sauren Bedingungen rnit Acetessigestern nur sehr schlecht und mit geringen Ausbeuten. Durch Zusatz katalytischer Mengen Athanthiol lauft die Kondensation jedoch glatt und mit guten Ausbeuten. Es wurden Bis(alky1-Chydroxy-pheny1)alkansaureester und -amide 4, 6 und 7 bzw. 8 aus Acetessigsaureestern, Lavulinsaureestern, 5-Oxohexansaureestern sowie Acetessigsaureamiden und Alkylphenolen hergestellt. Condensation Reactions of Keto Carboxylic Acid DerivativesUnder acidic conditions mono-and dialkylphenols react only poorly with acetic esters to give low product-yields. On addition of catalytic amounts of ethanethiol, however, condensation proceeds smoothly and in good yields. Bis(alkyl-4-hydroxyphenyl)-alkanoic esters and -alkanamides 4, 6, 7 and 8, respectively, were prepared from acetoacetic esters, levulinic esters, 5-oxohexanoic esters, and acetoacetamides by reaction with alkylphenols.Die Kondensation der niedrigsteil Ketocarbonsaure, der Brenztraubensaure, rnit Phenol wurde zuerst von Bottinger 1) beschrieben. Die Umsetzung wurde bei 0°C in Gegenwart von konzentrierter Schwefelsaure durchgefuhrt und fuhrte zu einer weiBen, amorphen Verbindung, deren Zersetzungspunkt uber 268°C lag. Diese Kondensationsreaktion wurde spater von Parris und Mitarbeiter 2) aufgegriffen und die Struktur des entstandenen Produktes durch IR-Spektroskopie, Bromanlagerung und durch ebullioskopische Messungen aufgeklart. Parris konnte zeigen, daB dabei ein polymeres Produkt 1 mit einer Molekulmasse von 1300 bis 1350 entstanden war.

A stereoselective synthesis of (.+-.)-nootkatone and (.+-.)-valencene via an intramolecular Sakurai reaction

“…The combined ethereal extracts were washed with 30 mL of brine, dried over anhydrous magnesium sulfate, filtered, and evaporated. Distillation of the crude residue at 103 °C (5 mmHg) afforded 6.17 g (70%) of 5,6-dimethyl-3-ethoxy-2-cyclohexenone, which was homogeneous by TLC: IR (neat) 3500, 2975, 2940, 2880, 2840,1675,1610,1445, 1420,1400, 1380,1360, 1335,1220, 1190, 1160.1110.1090.1040.1030, 960, 935, 900, 845, 825, 790, 710 cm"1; NMR (CCI4) 5.03 (s, 1 ), 3.80 (q, 2 H, J = 7 Hz), 2.25-1.45 (m, 4 ), 1.35 (t,3H,J = 5 Hz), 1.06 (d, 6 H, J = 6 Hz); mass spectrum, m/z 168 (M+); 13C NMR (CDC13) 201.81 (s), 175.75 (s), 101.42 (d), 63.94 (t), 34.74 (t), 31.76 (d), 19.62 (d), 13.94 (q), 12.74 (q), 10.90 (q) ppm. Anal.…”

“…Filtration and evaporation of solvent afforded crude 7. Chromatography of the crude product (elution with 4:1 hexane/ether; 6, Rf 0.65; 7, Rf 0.85) afforded 700 mg (54%) of 7, which was isolated as a mixture of E and Z isomers: IR (neat) 2950, 2250,1640,1610,1450,1405,1380,1360,1330,1280,1250,1220, 1200, 1190, 1110, 1095, 1060, 1035, 960, 855, 740, 700 cm'1; NMR (CC14) 5.03 (s, 1 H), 4.66 (m, 1 H), 3.73 (q, 2 H, =7 = 7 Hz), 2.23 (d, 2 H, =7 = 3 Hz), 1.70 (s, 3 ), 1.66 (s, 2 ), 1.35 (t, 3 H, =7=5 Hz), 0.95 (d, 3 H, =7 = 6 Hz), 0.90 (s, 3 H); mass 4-[3-Methyl-4-(trimethylsilyl)-2-butenyl]-4,5-dimethyl-3vinyl-2-cyclohexenone (1). To a solution of 700 mg (2.3 mmol) of 7 in 12 mL of tetrahydrofuran at 0 °C was added 2.95 mL (2.95 mmol, 1.0 M in THF) of vinyllithium, and the reaction was allowed to stir for 30 min at 0 °C.…”

“…Hz)5.06 (s, 1 H),3.7 (q, 2 H, =7 = 7 Hz), 2.2 (m,5 ),1.13 (t,3 H, =7 = 5 Hz), 0.96 (s, 3 ), 0.09 (d,3 H, =7 = 6 Hz).6-[3-Methyl-4-(trimethylsilyl)-2-butenyl]-5,6-dimethyl-3ethoxy-2-cyclohexenone(7). To a solution of 2.0 g(5.35 mmol) of ethyltriphenylphosphonium bromide in 16 mL of tetrahdyrofuran at 0 °C was added 4.0 mL (5.95 mol) of n-butyllithium (1.5 M in hexane), and the mixture was allowed to stir for 1 h while warming to room temperature.…”

Nucleophilic Acyl Substitutions of Esters with Protic Nucleophiles Mediated by Amphoteric, Oxotitanium, and Vanadyl Species

“…Octadecyl Acetoacetate, 2k (Including Enol Isomer). Data: mp 39−40 °C; IR (KBr) 2959 (m), 2915 (s), 2849 (s), 1746 (s), 1709 (m), 1465 (w), 1414 (w), 1370 (w), 1322 (m), 1263 (m), 1159 (m), 1053 (w), 1038 (w); 1 H NMR (400 MHz, CDCl 3 ) 12.08 (s, 1H, enol), 4.94 (s, 1H, enol), 4.09 (t, J = 6.8, 2H), 4.07 (t, J = 6.9, 2H, enol), 3.40 (s, 2H), 2.22 (s, 3H), 1.60 (quint, J = 7.1, 2H), 1.22 (bs, 30 H), 0.84 (t, J = 6.6, 3H); 13 C NMR (100 MHz, CDCl 3 ) 200.3, 175.2, 172.6, 167.0, 89.6, 65.4, 63.9, 50.0, 31.8, 29.9, 29.61, 29.58, 29.55, 29.5, 29.4, 29.3, 29.2, 29.1, 28.4, 25.8, 25.7, 25.6, 14.0; TLC R f 0.38 (EtOAc/hexane, 1/9); HR-MS (FAB+) calcd for C 22 H 42 O 3 + H: 355.3212, found: 355.3219.

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