Reaction of Zirconium Hydride with Carbon Tetrachloride

Influence of solvents and catalysts on the formation and hydrolysis of polyfunctional enoxysilanes derived from aucubin

“…Then the hydride migrates to furnish ketosilane 5b which was hydrolyzed to 5a (way b). Otherwise, we found that the use of BF 3 .Et 2 O as catalyst promotes the methylketone 7a formation. In that event, TMSDM reacts on the carbonyl giving a double homologation.…”

“…In that event, TMSDM reacts on the carbonyl giving a double homologation. Although the first steps of formation of compounds 5a and 7a are similar, for 7a, BF 3 .Et 2 O also participated to the hydrolysis of the trimethylsilyl group. 29 Once the intermediate 5a formed, TMSDM reacts again with the carbonyl activated by BF 3 .Et 2 O (way c).…”

“…As described before, the reaction of 3a with TMSDM in presence of TMSOTf has led specifically to the enoxysilane 4 having the oxepin ring with high yield compared to the experience with AlCl 3 (Table 2, Entry 1). 16 Using a catalytic amount of a solution of Yb(OTf) 3 in THF, the stereoselectivity of the formation of enoxysilanes has been lost because 4 and 8 were formed with equal ratio (Table 2, Entry 2). Enoxysilanes 4 and 8 presented a structural analogy.…”

“…Various catalysts which were defined previously to react with TMSDM and carbonyls, 26 have also been tested. No reaction occurred with AlMe 3 and MgBr 2 while the use of BF 3 .Et 2 O generated the homologated methylketone 7.…”

“…It has been the first iridoid glucoside isolated in 1902 by E. Bourquelot at the "Ecole de Pharmacie de Paris". 2 After its structural elucidation by H. Uda 3 and by J. Grimshaw in 1960, 4 this naturally occurring material devoid of cytotoxic activity, [5][6][7] is used for several decades by organic chemists for the synthesis of chiral building blocks or scaffolds.…”