Structural and Synthetic Insights into Sodium-Mediated-Ferration of Fluoroarenes

Exploiting chemical cooperation between Na and Fe(II) within the bimetallic base [dioxane ⋅ NaFe(HMDS)₃] ( I ), (dioxane=1,4-dioxane, HMDS=N(SiMe₃)₂) the selective ferration of fluorobenzene, 1-fluoronaphthalene, 1,4-difluorobenzene, 1,2,4-trifluorobenzene, 1,3,5-trifluorobenzene, 1-bromo-3,5-difluorobenzene, 3-fluoroanisole and 3,5-difluoroanisole has been realized, affording sodium ferrates [dioxane ⋅ Na(HMDS)(2-F-C₆H₄)Fe(HMDS)]_∞ ( 1 ), [dioxane ⋅ Na(HMDS)(2-F-C₁₀H₆)Fe(HMDS)]_∞ ( 2 ), [dioxane ⋅ {Na(HMDS)(2,5-F₂-C₆H₃)Fe(HMDS)}₂]_∞ ( 3 ), [dioxane ⋅ {Na(HMDS)(2,3,6-F₃-C₆H₂)Fe(HMDS)}₂]_∞ ( 4 ), [(dioxane)_1.5 ⋅ Na(HMDS)(2,4,6-F₃-C₆H₂)Fe(HMDS)]₂ ( 5 ), [(dioxane)_1.5 ⋅ {Na(HMDS)(4-Br-2,6-F₂-C₆H₂)Fe(HMDS)₂] ( 6 ), [{(dioxane)₂ ⋅ Na₂Fe(HMDS)₂(2-methoxy-6-F-C₆H₃)}⁺{Fe(HMDS)₃}⁻]_∞ ( 7 ) and [dioxane ⋅ {Na(HMDS)(4-methoxy-2,6-F₂-C₆H₂)Fe(HMDS)}₂]_∞ ( 8 ), respectively. Reactions take place under mild reaction conditions, with excellent control of the selectivity and no competing C−F bond activation is observed. Showcasing complex polymeric arrangements in some cases, the structures of compounds 1 – 8 have been determined by X-ray crystallographic studies. In all cases, the Fe(II) centers occupy the position in the relevant fluoroarene that was previously filled by a proton, confirming that these metallations are actually ferration processes whereas the Na atoms prefer to form Na⋅⋅⋅F dative interactions. Compounds 1 – 8 are thermally stable and do not undergo benzyne formation (through NaF elimination) and their formation contrasts with the inertness of Fe(HMDS)₂ which fails to act as a base to metallate fluoroarenes.     

The CH-functionalization of B-substituted organosilicon derivatives of polyhedral carboranes as a way to obtain new materials

The metallation of CH-groups in carboranyl polyhedra with n-butyllithium followed by end-capping with chloro(di-methyl)vinylsilane was explored using a model B-substituted organosilicon derivative obtained previously, the optimal conditions being Et₂O, –10 →20 °C, total processing time 125 min. This procedure was applied to prepare a zero-generation polyfunctional B-substituted carborane-carbo-silane dendrimer G₀-4 cages.     

Main Group Metal-Mediated Transformations of Imines

Main-group-metal-mediated transformations of imines have earned a valued place in the synthetic chemist's toolbox. Their versatility allows the simple preparation of various nitrogen containing compounds. This review will outline the early discoveries including metallation, addition/cyclisation and metathesis pathways, followed by the modern-day use of imines in synthetic methodology. Recent advances in imine C−F activation protocols are discussed, alongside revisiting “classic” imine reactivity from a sustainable perspective. Developments in catalytic methods for hydroelementation of imines have been reviewed, highlighting the importance of s-block metals in the catalytic arena. Whilst stoichiometric transformations in alternative reaction media such as deep eutectic solvents or water have been summarised. The incorporation of imines into flow chemistry has received recent attention and is summarised within.