New Catalytic Route to Alkynylgermanes

Abstract

Vinyl-trisubstituted germanes react selectively with terminal alkynes in the presence of compounds containing Ru-H and Ru-Ge bonds with formation of functionalized alkynylgermanes. The reaction opens the first transition metal catalytic route for the preparation of this class of organogermanes, which are useful reagents for organic synthesis. The mechanism elucidated by NMR spectroscopic study of stoichiometric reactions shows that this process is a new catalytic activation of an sp-hybridized C-H bond involving the previously discovered activation of the dC-Ge bond. † Dedicated to Professor Florian Domka on the occasion of his 75th birthday.

Improved Syntheses of Versatile Ruthenium Hydridocarbonyl Catalysts Containing Electron‐Rich Ancillary Ligands

“…Triple bonds can also be activated: Beatty has reported that 2 functions as a precatalyst for the reductive hydrolysis of nitriles, [21] while Marciniecs group recently developed new catalytic routes to functionalized alkynylylsilanes and alkynylgermanes by using 2 to activate sp-hybridized carbon-hydrogen bonds. [22,23] Analogous catalysts containing an N-heterocyclic carbene ligand (3, Figure 1), though less explored, are now beginning to see use in olefin hydrogenation and isomerization. [10,[24][25][26] In particular, 3a is implicated in the synthesis of saturated neoglycopolymers relevant to tissue engineering via tandem ROMP-hydrogenation, [10] while Arisawa, Nishida and co-workers have exploited the isomerization activity of 3b to develop new routes to indoles and related heterocycles via cycloisomerization of 1,6-dienes.…”

A New Catalytic Route to Boryl‐ and Borylsilyl‐Substituted Buta‐1,3‐dienes

“…Similarly to the previously described trans-metalation reactions of vinylmetalloid with olefins and acetylenes [2][3][4][5] (for a review see ref.…”

“…The latter is preferred in this case to yield the RuÀvinylene complex (instead of RuÀsilyl and RuÀgermyl complexes, which are preferred in the previous systems [4,5] ) directly responsible for the final step yielding co-dimerisation products.…”

“…This is the reason why contrary to vinylsilane [4] and vinylgermane, [5] the metalation of acetylene with vinylboronate was not observed during the catalytic process. Instead, the codimerisation of vinylboronate with most terminal acetylenes (except phenylacetylene) was noted.…”

“…(2)]. [4][5] The reactions are widely recognised as efficient catalytic activations of =CÀH, CÀH and =CÀE bonds of a vinylmetalloid with evolution of ethylene. The mechanisms of these reactions involve the insertion of vinyl-E into the TM À H bond and b-hydrogen transfer to the metal with elimination of ethylene and generation of the TM À E bond.…”