1,1-Organoboration of Trimethyl-l-propynyltin Using Diorganoboryl-Substituted Ferrocenes

Abstract

Ferrocenes, Trimethyl-l-propynyltin, 1,1-Organoboration, Alkenyltin Compounds, X-Ray The reactions of various diorganoborylferrocenes, F c -B R 2 [1, R = Me (a), Et (b), 'Pr (c), 'Bu (d), Ph (f), R2B = 9-borabicyclo[3.3.1]nonyl (e)] and 1,1 '-bis(9-borabicyclo[3.3.1]nonyl)-ferrocene (2) with trimethyl-l-propynyltin (3) were studied, and the products of the 1,1-organoboration were characterized as the alkenyltin compounds 4 -6 by 'H, UB, 13C and 119Sn NMR. In the cases of l a -I d and If, there is competition between the transfer of a ferrocenyl group and the other organyl groups R from boron to carbon, whereas in the case of the 9-borabicyclo[3.3.1]nonane derivatives le and 2, the enlargement of the bicyclic system takes place selectively (compounds 4e and 6). The molecular structure of the product 6, obtained from the reaction between the l,l'-diborylated ferrocene 2 and two equivalents of 3, was determined by single crystal X-ray analysis (space group P2x!c\ monoclinic; Z = 4, a = 958.3(2), b = 1610.4(3), c = 2405.3(5) pm and ß = 90.33(3)°).

Multidentate Lewis acids: synthesis, structure and mode of action of a redox-based fluoride ion sensorElectronic supplementary information (ESI) available: details of NMR and UV/Vis spectroscopic measurements. See http://www.rsc.org/suppdata/cc/b2/b200828a/

“…12 The torsion angle of 54.4° [for •C(5)-centroid-centroid-C(24)] finds precedent among similar molecules only in 1,1A-Fc(BC 11 H 17 SnCH 3 ) 2 . 13 That the structure of 2 does not vary appreciably between crystals obtained from light petroleum (bp 40-60 °C) and those of the solvate 2•2C 6 H 6 rules out interaction with solvent molecules (e.g. p-stacking between phenyl rings and benzene solvent) as a conformationally significant factor.…”

Transmetalation as a Route to a Cyclic Heteronuclear Bifunctional Lewis Acid Containing Tin and Gallium

“…[16][17][18][19] Interestingly, heteronuclear systems that combine a group 13 and a heavier group 14 element have received only limited attention. [20][21][22][23] This approach should, however, yield polyfunctional Lewis acids whose affinity for Lewis bases differs from that of the homonuclear systems. In this paper, we report that tingallium ligand exchange occurs between 1,8-bis(trimethylstannyl)naphthalene 24 (1) and gallium trichloride to yield a heteronuclear bifunctional Lewis acid with a central eight-membered stannagallacycle.…”

Frustrated Lewis pairs incorporating the bifunctional Lewis acid 1,1′-fc{B(C6F5)2}2: reactivity towards small molecules

“…1,1'-fc(BBr2)2, FcB(C6F5)2 (1), and NHCs (IMes, IDipp, IMesCl2, 6Mes and 6Dipp) were prepared by literature routes. 14,15,36 Syntheses of novel compounds 1,1'-fc{B(C6F5)2}2 (2): To a solution of bromopentafluorobenzene (5.89 mL, 47.5 mmol) in hexane (30 mL) at -78˚C, was added dropwise n BuLi (29.7 mL of a 1.6 M solution, 47.5 mmol) and the mixture stirred at -78˚C for 45 min. CAUTION: LiC6F5 IS KNOWN TO EXPLODE AT TEMPERATURES ABOVE -40 o C. A solution of 1,1'-fc(BBr2)2 (6.10 g, 11.6 mmol) also in hexane (150 mL), was then added dropwise at -78 o C, and the resulting mixture allowed to warm slowly to room temperature over a period of 12 h. After removal of volatiles in vacuo the product was extracted into hot hexane.…”

“…12c With this in mind, a more direct synthesis from LiC6F5 was targeted, drawing on the route which we have previously developed to prepare 1 from FcBBr2 (Scheme 3). 14 The one-pot literature synthesis of bifunctional 1,1'-fc(BBr2)2 from ferrocene and BBr3, 15 is followed by reaction with slightly greater than four equivalents of LiC6F5, generated in situ from n BuLi and C6F5Br. Although LiC6F5 is notoriously explosive above -40 o C, the synthetic protocol that we employ means that [as in the synthesis of Me2Sn(C6F5)2] it never warms above -78 o C, and so can be safely and reproducbly used in the synthesis of 2.…”