ansa-Metallocene Derivatives. 30. Syntheses and Structures of Titanocene, Zirconocene, and Vanadocene Dichloride Complexes with Two Ethanediyl Bridges

Strategies for the Synthesis of Chiral Carbon‐Bridged Group IV ansa‐Metallocenes

“…The double‐Skattebøl approach was also applied by Brintzinger and co‐workers to synthesize double‐bridged ansa ‐titanocenes and by Buchwald and co‐workers to prepare the conformationally rigid chiral ligand 30 (Scheme b) . Here, ligand 30 obtained after the carbene rearrangement was directly treated with TiCl 3 ⋅3 THF.…”

“…The double-Skattebøl approach was also applied by Brintzinger and co-workerst os ynthesize double-bridged ansa-titanocenes and by Buchwald and co-workers to prepare the conformationally rigid chiral ligand 30 (Scheme 8b). [35,36] Here, ligand 30 obtained after the carbener earrangement was directly treated with TiCl 3 ·3 THF.T his way,b romide salts were still present,w hich led to am ixture of titanocene dihalides (31)(32)(33) that werec onverted into the titanocene dibromide 33 by treatment with boron tribromide. The authors noted that the Scheme5.Synthesis and resolution of achiral ansa-titanocene.…”

Ethanol catalyzed synthesis of titanocene aryl carboxylate complexes and crystal structure of (η5-C5H5)2Ti(2-OH-5-S–O2CC6H3)2

“…After stirring for 12 h, the reaction system was heated to boil until there was no precipitate present, then cooled again with ice-bath and filtered. The resulting solid was dissolved by ethyl ether, the insoluble precipitate was filtered off, and the filtrate was dried and recrystallized from Et 2 (1) NaOH (0.10 g, 2.5 mmol) and ethanol (2 mL) were added to the mixture of Cp 2 TiCl 2 (0.248 g, 1.0 mmol) and 5,5 0 -DTDS (0.384 g, 1.0 mmol), which were dissolved in CHCl 3 (40 mL)/Et 2 O (10 mL), previously. After stirring for 30 min at room temperature, the reaction solution was dried with anhydrous MgSO 4 and filtered.…”

“…Derivatives of Cp 2 TiCl 2 , have the subject of much study in recent years, not only of their fascinating structural diversity [1][2][3][4][5][6], electrical, magnetic, optical properties [7][8][9][10][11][12][13], but also of their activity as anti-tumor drugs [14][15][16][17][18][19][20][21][22]. Generally, reported synthetic methods of titanocene derivatives require in anhydrous, aprotic organic solvent conditions [23][24][25][26] due to they are not stable in open air, suffering from facile hydrolysis.…”

Enantioselective Hydrogenations with Chiral Titanocenes

“…This problem may also be resolved by incorporation of a double-bridge in the ligand, to form complexes such as 40-42 [47,48,49] or disilyl-bridged 43 titanocenes [50,51]. Because of the rigid structure of these complexes, only one titanocene enantiomer is obtained.…”