Efficient and Stereoselective Synthesis of Bicyclo[3.2.1]octan-8-ones: Synthesis and Palladium-Catalyzed Isomerization of Functionalized 2-Vinyl-2,3,3a,4,5,6-hexahydro-2,3-benzofurans

Abstract

Reduktion des Unreduzierbaren: Die Einführung eines Lanthanoid‐Kations in die leerstehende Koordinationstasche eines Uranyl‐Pacmankomplexes führt zu einer Einelektronenreduktion und der Bildung eines fünfwertigen Uranyl‐Seltenerd‐Komplexes mit Uranyl‐Oxo‐Seltenerd‐Bindungen (siehe Schema; py=Pyridin, R=SiMe3).

Chemoselective, Regioselective, and E/Z-Diastereoselective Synthesis of 2-Alkylidenetetrahydrofurans by Sequential Reactions of Ambident Dianions and Monoanions

“…The configuration of 2-alkylidenetetrahydrofurans 3 was proven by NOESY experiments and by comparison of the chemical shifts of the hydrogen atoms of the exocyclic double bond with those of related compounds (Table ). , As expected, characteristic chemical shifts in the range of δ = 5.15−5.31 and δ = 4.70−4.90 were observed for all E - and Z -configured ester-substituted 2-alkylidenetetrahydrofurans, respectively. Likewise, a characteristic chemical shift (δ = 6.55) was observed for the E -configured phenyl-substituted 2-alkylidenetetrahydrofuran 3l .…”

Regioselective synthesis of functionalized 3,5-diketoesters and 2,4-diketosulfones by uncatalyzed condensation of 1-methoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with α,β-unsaturated acid chlorides and sulfonyl chlorides

“…12, 13 b-Ketosulfones are available by reaction of enolates with disulfides and subsequent oxidation of the sulfide moiety. 14 Kamigata et al reported the synthesis of b-ketosulfones by Ru(PPh 3 ) 2 Cl 2 -catalyzed reaction of silyl enol ethers with sulfonyl chlorides. 15 However, the scope of this method is limited to acetophenone-derived silyl enol ethers.…”

“…Starting with 12a (1.02 g, 5.8 mmol) and 1a (3.00 g, 11.5 mmol), dissolved in CH 2 Cl 2 (10 mL), 13a was isolated as a yellow solid (0.90 g, 61%), mp 62-64 • C. (KBr, cm −1 ): m = 3439 (w), 3103 (s), 3068 (s), 2959 (s), 2911 (s), 2854 (s), 1747 (m), 1724 (m), 1587 (s), 1481 (s), 1446 (m), 1439 (s), 1409 (s), 1373 (s), 1339 (m), 1323 (m), 1264 (s), 1205 (m), 1154 (m), 1127 (s), 1090 (s), 1072 (s), 1057 (s), 1024 (s), 948 (s), 869 (s), 796 (s), 748 (s), 720 (s), 688 (s), 652 (s), 607 (s), 541 (s), 528 (s), 461 (s). MS (EI, 70 eV): m/z (%) = 256 (M + , 2), 225 (19), 224 (11), 192 (31), 183 (25), 174 (9), 160 (18), 141 (87), 135 (17), 125 (17), 118 (13), 115 (39), 101 (45), 94 (12), 91 (19), 78 (20), 77 (100), 74 (14), 69 (16), 59 (13), 51 (37), 43 (14)…”

Palladium-Catalyzed [1,3]-O-to-C Rearrangement of Pyrans toward Functionalized Cyclohexanones

“…Nonetheless, Trost and Tsuji independently demonstrated that furan-based enol ethers can be transformed to cyclopentanones in good yield, in the presence of a low-valent palladium source . This concept was later used by Langer in an intramolecular variant in order to access bicyclo[3.2.1]octan-8-ones . Notably, all of these examples exploited the intermediacy of a stabilized enolate by appending electron-withdrawing substituents on the enol ether moiety.…”