Interaction of TiF4 with the donor solvents SO2, PhCN, and MeCN

A Direct and Stereoretentive Synthesis of Amides from Cyclic Alcohols

“…Although currently under study by various groups for use in dental varnishes, [15] titanium(IV) fluoride has received only modest attention from the organic synthesis community [16] probably due to its moderate complexing ability, [17] propensity for oligomer complex formation, and sparing solubility in typical reaction solvents. Following up on a report indicating that TiF 4 can be solubilized as nitrile complexes, [18] we hypothesized that a fluorination reaction might still be possible with added nitrile. To our surprise, the subsequent reaction of this solubilized reagent with the chlorosulfite ester of l -menthol failed to give the expected fluoride but instead afforded amide product 1a after aqueous workup with complete retention of configuration (table 1).…”

“…Indeed, our subsequent studies revealed that a number of Ti(IV) species can be used to catalyze halosulfite reactions leading to alkyl halides in excellent yields under mild conditions with nearly exclusive retention of configuration. [19] Based on previous studies, [18] we suspected that multiple equivalents [20] of TiF 4 and nitrile would be necessary for our amidation reaction. Indeed, the optimal ratio of benzonitrile to TiF 4 appears to be 4:1.…”

Br2F7− and Br3F10−: peculiar anions showing μ2- and μ3-bridging F-atoms

“…[2][3][4][5][6][7][8][9][10][11][12][13] The highly strained tri(m-F)-bridges between various elements 1 are scarce with only some examples in the literature. [2][3][4][5][6][7][8][9][10][11][12][13] Bridges among three atoms (m 3 -F) are even more rare; [14][15][16][17][18][19][20][21] however, m 4 -F 22,23 and even cage-like m 6 -F 22,24,25 coordination types are known. In the vast majority of these compounds the fluorine atom bridges either metal atoms (thus, forming homoor hetero (oligo-)nuclear complexes), or, more rarely, metal and nonmetal atoms.…”

“…134.75 (9) 140.27 (6) 130.08(4) F(5)-M(1)-F (1) 175.17 (8) 176.18 (6) 176.0(6) F(7)-M(2)-F (1) 176.04 (8) 176.44 (7) 176.0(6) Tilting angle between F 3 M-m-F-MF 3 CsAu 2 F 7 (which is similar in terms of the anion geometry but is not structurally isotypic) 40 are shown in Table 3. In comparison to the Br 3 F 10 À anions, a shortening of the Br-m-F-Br bridges of circa 0.1 to 0.2 Å is observed which may be due to smaller Coulomb repulsion between the two Br atoms.…”

Activation reactions of 1,1-dialkoxoalkanes and unsaturated O-donors by titanium tetrafluoride

“…Complex TiF 4 (dme) is obtained by straightforward 1:1 reaction of TiF 4 with 1,2-dimethoxyethane (dme) [9]. Polymeric fluorine-bridged complexes may be obtained with weak Lewis bases such as pyridine [7c] and benzonitrile [10] Compounds of formula TiF 4 L 2 show generally the cis-configuration although cis-trans equilibria in solution have been observed when strongly donating, sterically hindered ligands are involved [8a, 11].…”