TiCI4-THF

TiCI4(THF)2 + LiCH2EMe3 --Ti(CH2EMe3)4 TiCI(CH2EMe3)3 LiSi(SiMe3)3(THF)3 r ... 

E19a, 653 [Carbonsaure + En/ Cyclisierung (intra)] trani-2-Methyl-5-oxo-3-phenyl-tetrahydro- E2Ib, 1194 (3-Ar-2,5-dioxo-THF + H3C-Li/TiCI4)... 

Titanium complex (1).2 To Mg (7.0 g, 0.29 at.g) in THF (50 mL) was added TiCI4 (1.9 g, 10 mmol) at -78°C under Ar. After degassing, the mixture was stirred at 20°C under N2 for 16 h with a change of color and exothermicity. The unreacted Mg was removed by filtration under N2 and the filtrate was stirred for 1 h at 20°C under C02. The reaction mixture under ice cooling was treated with hexane (1 mL) and the precipitate 1 was filtered, washed with Et20 and dried in vacuum. 

Scheme 15 Synthesis of the 3,3-di-O-gallate (98) of procyanidin B-2 (5). Reagents and conditions (a) TiCi4, CH2Ci2/THF, RT (b) 20% Pd(OH)2/C, H2, THF/Me0H/H20, RT (c) 3,4,5-tris(benzyioxy)benzoyi chioride, 4-DMAP, pyridine, RT.

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