Ge(ii) cation catalyzed hydroboration of aldehydes and ketones

Abstract

The catalytic utility of a germylene cation 4 is reported. In the presence of compound 4, a variety of aldehydes and ketones can be hydroborylated using HBpin.

Heavier Tetrylenes as Single Site Catalysts

“…They prepared an aminotroponate based germylene cation [(i-Bu) 2 ATIGe][GaCl 4 ](38) (ATI = aminotroponate) along with other weakly coordinated Ge(II) cations, 36 and 37 and utilized them for the hydroboration of a variety of substrates (Scheme 32). [78] The X-ray structure of 38 displays a well isolated cationic Ge(II) centre, while 37 has a weakly coordinated triflate group to the germanium center. It is important to mention that chlorine atoms of [GaCl 4 ] À anion are interacting with Ge(II) center in 38.…”

“…It is important to mention that chlorine atoms of [GaCl 4 ] À anion are interacting with Ge(II) center in 38. [78] Hydroboration of carbonyl substrates with HBpin was initially conducted in the presence of and 38 as catalysts. It was found that the catalytic efficiency of 37 is better than that of 38 and that was attributed to the steric crowding around the germanium atom in 38.…”

“…In the following step, HBpin undergoes σ-bond metathesis with 39 b to afford the hydroborylated aldehyde/ketone and the active catalyst 37. [78] Further, the same group synthesized an aminotroponate based stannylene (40) and utilized it as catalyst for the hydroboration of carbonyl compounds (Scheme 35). [79] 40 exists in dimeric form due to the Sn•••O interactions.…”

Hydroboration of Aldehydes, Ketones, and Carbodiimides Promoted by Mono(imidazolin‐2‐iminato) Hafnium Complexes

“…The hydroboration of C=O bonds is particularly impressive and it is strengthening its prestige as one of the utmost useful and most widely used reactions for the pharmaceutical industry . Carbonyl hydroboration catalysts include alkaline earth metals,, transition metals, group 13 metal catalysts, lanthanide, actinides, and other unique and sophisticated systems . In addition to the hydroboration of C=O bonds, the selective monohydroboration of carbodiimides to produce amidinates is also of great interest, since these systems play an important role in coordination chemistry …”

Hydrophosphination using [GeCl{N(SiMe3)2}3] as a pre-catalyst

“…[5][6][7] Subsequently, there have been numerous reports on low-coordinate Ge(II) species acting as efficient pre-catalysts for the hydroboration of carbonyls (Scheme 1b). [8][9][10][11] This reactivity has also been extended to the catalytic cyanosilylation of aldehydes. 12,13 Despite this progress, lactide polymerization and carbonyl hydrofunctionalization are commonly reported catalytic transformations, 14,15 therefore a desire remains to uncover use for germanium (both Ge(II) and Ge(IV)) in the catalysis of a wider range of transformations.…”