Light-Promoted Organic Transformations Utilizing Carbon-Based Gas Molecules as Feedstocks.

Carbon-based gas molecules are readily available feedstocks and are widely used in industry as building blocks or fuels. However, their application in the synthesis of fine chemicals has been hampered due to operational complexity, poor reaction efficiency and selectivity. Recent development of photoredox-promoted transformations using such gaseous reagents has received considerable attention from the synthetic community. In this review, efforts in developing light-promoted organic transformations using carbon-based natural gases as C1 or C2 feedstocks and to overcome the associated challenges are briefly summarized.

A Radical Smiles Rearrangement Promoted by Neutral Eosin Y as a Direct Hydrogen Atom Transfer Photocatalyst.

A visible-light-mediated radical Smiles rearrangement has been achieved using neutral eosin Y as a direct hydrogen atom transfer (HAT) photocatalyst. Novel N-heterocycles as single diastereomers featuring an isothiazolidin-3-one 1,1-dioxide moiety are directly accessed by this method. A wide range of functional groups can be incorporated in the products by employing diverse aldehydes and N-(hetero)arylsulfonyl propiolamides. The transformation proceeds through a cascade of visible-light-induced HAT, 1,4-addition, Smiles rearrangement, 5-endo-trig cyclization, and a reverse HAT process. Preliminary biological studies of the highly functionalized heterocyclic compounds suggest potential anticancer activity with some of the synthesized compounds.

Visible-light-mediated deuteration of silanes with deuterium oxide.

Isotopically labeled compounds are highly desirable as they can serve as both mechanistic probes in chemistry and diagnostic tools in medicinal research. Herein, we report an unprecedented visible-light-mediated metal-free deuteration of silanes using D2O as an inexpensive, readily available, and easy to handle deuterium source. A broad range of aryl- and alkyl-substituted silanes were deuterated with high deuterium incorporations and yields. Furthermore, a 100 gram-scale synthesis was demonstrated using continuous-flow micro-tubing reactors, where enhanced reaction efficiency was obtained. The photoredox-catalyzed polarity matched hydrogen atom transfer (HAT) between silanes and the thiol HAT catalyst was responsible for the efficient deuteration.