Visible-light-mediated deuteration of silanes with deuterium oxide

Abstract

An unprecedented visible-light-mediated metal-free deuteration of hydrosilanes using D2O as a deuterium source was developed.

Photoredox‐Mediated Hydrogen Isotope Exchange Reactions of Amino‐Acids, Peptides, and Peptide‐Derived Drugs

“…This amine is then oxidized via as ingle electron transfer (SET) from the excited photocatalyst (E 1/2 {*Ir III /Ir II } =+1.51 Vand E 1/2 {nBuNH 2 } % + 1.40 V) [18] to generatet he a-amino radical 5, which then undergoes aH AT process with the deuterated thiol (generated in situ) to form the deuterated amine 1.F inally,t he catalytic cycle is closed through aS ET from the reduced Ir II speciest ot he thiol radical( E 1/2 {Ir III /Ir II } = À1.42 Vand E 1/2 {thiol} %À0.85 V), [19] enabling the regeneration of Ir III and the thiolate anion. With the need for as trong base like BTMG to achieve a high deuterium incorporation (see Ta ble 1, Figure 2A), we hypothesize that this pathway,w hichi sc onsistent with previously described mechanistic explanations that have been reported for similars tructures, [15] is more likely than an alternative pathway for the formation of the a-amino radical which would involve aH AT process with the thiol radical.…”

“…A major breakthrough towards as implified and easy to use HIE protocol, using photoredox-mediated activation, was reported by MacMillan et al in 2017 [14] detailing the deuteration and tritiation of complex tertiary amines at the a-position to the nitrogen, with good to high selectivity.M ore recently,W ue tal. have reported ap rocedure for the deuteration of silanes, using ap hotoredox-catalyzed polarity-matched hydrogena tom transfer (HAT) with thiols, [15] and this year Wang et al have developedabiphasic protocol, using at ungsten complex as a photocatalyst for the deuteration of aromatic and aliphatic aldehydes. [16] To the best of our knowledge,t hese are the only examples reported so far which combinet he principles of photoredox-catalysis and HIE.…”

“…We started our studies with HIE reactions of our model com-poundC bz-lysine methylester [H]-1 under MacMillan's reaction conditions, [15] with unfortunately very limited success (Figure 2A,T able 1, entries 1a nd 2: 0t o0 .7 D). However,b y screening different bases, solvents and photocatalysts, whilst using triisopropylsilanet hiol as aH AT mediator and aP ennOC integrated photoreactor m1 equipped with a4 50 nm LED module (l = 450 nm) as light sources ystem,w ei dentified improvedc onditions, achieving 1.6D incorporation (Figure 2A, Ta ble 1, entry 5; see Supplementary Information for more details).…”

Visible light driven deuteration of formyl C–H and hydridic C(sp3)–H bonds in feedstock chemicals and pharmaceutical molecules

“…In the presence of excess amounts of D 2 O, the H/D exchange of the thiol catalyst leads to dominant formation of deuterated thiol. 18 The carbon radical abstracts a deuterium atom from the deuterated thiol to deliver the desired deuterated product and a thiyl radical. A single electron transfer between the thiyl radical and [W 10 O 32 ] 5À H + would regenerate the TBADT catalyst and deuterated thiol aer deuteration with D 2 O.…”

“…17 Our lab has reported a related visible-light-mediated deuteration of silanes using D 2 O as the deuterium source through the synergistic effect of a photoredox catalyst and a thiol catalyst. 18 However, the substrate scope of photoredox catalyzed C(sp 3 )-H functionalization is limited, because it is successful only when the redox potential of the C-H substrate is matched with that of the photocatalyst. 19 Wang et al have recently reported a H/D exchange at formyl groups of both aromatic and aliphatic aldehydes, by merging a photoredox catalyst, a hydrogen atom transfer (HAT) catalyst, and a thiol catalyst.…”