Catalytic Ionic Hydrogenation

Ionic and Organometallic‐Catalyzed Organosilane Reductions

“…1 -4 Similar chemistry is observed when molecular hydrogen 5,6 or various hydrocarbons 7 -9 are used as hydride sources; these methods have been reviewed previously and are not covered herein. The use of organosilicon hydride-metal catalyst mixtures 10 -12 for effecting reductions is included in this review, but use of trichlorosilane-tertiary amine combinations 13 is not.…”

“…This results in the formation of the corresponding ether. This reaction can be carried out employing PhSiH 3 /(PPh 3 )(CO) 4 MnC(O)Me, 295 PhSiH 3 /Mn(CO) 5 Br, 295 Cl 3 SiH/γ -irradiation, 296 or Et 3 SiH/TiCl 4 /TMSOTf. 297 The reduction of lactones to cyclic ethers is nicely accomplished with the EtMe 2 SiH/ruthenium catalyst system 57 (Eq.…”

“…143). 280 The same transformation can be carried out with Et 3 SiH/TiCl 4 297 or PhSiH 3 /Mn(CO) 5 Br. 295 The reductive etherification of esters occurs by treating an ester with Et 3 SiH/ZnCl 2 281,282 or Ph 3 SiH/(C 6 F 5 ) 3 B, 115 and with Ph 2 MeSiH/Mn(CO) 5 C(O)Me.…”

“…The TunaPhos ligands of general structure 114, when complexed with [RuPhCl 2 ] 2 , bring about the asymmetric hydrogenation of β-keto esters with The industrially important cis-(+)-methyl jasmonate 119 is conveniently prepared by the hydrogenation of enone 120 with Me-DuPHOS and [Ru(1,2 : 5,6-ηcod)(η 3 -methallyl) 2 [1,5]dioxonin) ruthenium catalyzes the hydrogenation of α-phthalimido ketones with enantioselectivities of >94%, 651 leading to a highly enantioselective route to β-aminoethanols.…”

Recent progress towards ionic hydrogenation: Lewis acid catalyzed hydrogenation using organosilanes as donors of hydride ions

“…With the proper selection of a hydrogenating pair or catalyst, high reactivity is generally achieved under mild reaction conditions with broad range of substrate scope and excellent functional group tolerance. 22,23 More importantly, some special products can be obtained by using ionic hydrogenation, including diverse heterocycle building blocks. Regarding the reaction mechanism, the addition of a proton to generate a cation is the rst step of this procedure, which then reacts with a hydride ion to give the corresponding hydrogenation product.…”