The synthesis ofα-amino acid from imines with different carbonyl sources is attractive for both synthetic organic and medicinal chemistry communities.Imines,which were easily available from the corresponding ketones and amines,were employed as one of the most ideal precursors.Traditionally,cyanation and subsequent hydrolysis were required to install the carboxyl group^([1]).In these cases,the toxicity of the cyanation reagents limited its further synthetic applications in organic chemsitry.Besides,metal activation of imine substrates to make the organometallic intermediate and trap CO_(2) to give the desiredα-amino acid were also developed by many groups(Scheme 1A).The utilization of stoiochiometric amounts of metal reagents was required to realize the transformation.Recently,Yu reported a novel photocatalytic reductive carboxylation protocol for synthesis ofα-amino acid from imines with CO_(2)as the carbonyl source^([2]).
Substantial effects of photochemical reaction losses of volatile organic compounds(VOCs)on factor profiles can be investigated by comparing the differences between daytime and nighttime dispersion-normalized VOC data resolved profiles.Hourly speciated VOC data measured in Shijiazhuang,China from May to September 2021 were used to conduct study.The mean VOC concentration in the daytime and at nighttime were 32.8 and 36.0 ppbv,respectively.Alkanes and aromatics concentrations in the daytime(12.9 and 3.08 ppbv)were lower than nighttime(15.5 and 3.63 ppbv),whereas that of alkenes showed the opposite tendency.The concentration differences between daytime and nighttime for alkynes and halogenated hydrocarbonswere uniformly small.The reactivities of the dominant species in factor profiles for gasoline emissions,natural gas and diesel vehicles,and liquefied petroleum gas were relatively low and their profiles were less affected by photochemical losses.Photochemical losses produced a substantial impact on the profiles of solvent use,petrochemical industry emissions,combustion sources,and biogenic emissions where the dominant species in these factor profiles had high reactivities.Although the profile of biogenic emissions was substantially affected by photochemical loss of isoprene,the low emissions at nighttime also had an important impact on its profile.Chemical losses of highly active VOC species substantially reduced their concentrations in apportioned factor profiles.This study results were consistent with the analytical results obtained through initial concentration estimation,suggesting that the initial concentration estimation could be the most effective currently availablemethod for the source analyses of active VOCs although with uncertainty.
Nitroso compounds have emerged as highly valuable reaction partners or reagents in organic synthesis due to their rich reactivity.The versatile profile of these compounds allows them to function as electrophiles,nucleophiles,diradicals,and radical acceptors in diverse transformations.In recent years,notable progress has been made in harnessing photochemical reactions with nitroso compounds to prepare N,O-containing structures using mild and eco-friendly conditions.Various nitroso compounds like nitrosoarenes,acyloxy nitroso compounds,N-nitrosoamines and nitrites have received significant attention for their ability to introduce NO moieties into complex molecules that are otherwise difficult to access.In this review,we provide an overview of the recent advancements in the visible light-induced conversion of nitroso compounds,with particular emphasis on their role as bifunctional reagents and acceptors of radicals,carbenes and nitrenes.
