RESUMO
A copper-catalyzed three-component tandem reaction has been developed for the convenient and practical synthesis of 1,4-benzothiazines. A variety of terminal alkynes and 2-iodo/bromophenyl isothiocyanates underwent this one-pot cyclization with aqueous ammonia to afford 1,4-benzothiazines in moderate to good yields.
RESUMO
An iron-promoted tandem carboxamidation and cyclization between aryl isonitriles and formamides has been developed. The one-pot strategy can be applied to a wide range of 2-isocyanobiphenyls and formamides with excellent functional group tolerance for the synthesis of phenanthridine-6-carboxamides in moderate to excellent yields.
Assuntos
Cloretos/química , Compostos Férricos/química , Formamidas/química , Nitrilas/química , Fenantridinas/química , Fenantridinas/síntese química , Catálise , Ciclização , Estrutura Molecular , EstereoisomerismoRESUMO
The toxic effect of excessive manganese (Mn) on photosystem II (PSII) of woody species remains largely unexplored. In this study, five Mn concentrations (0, 12, 24, 36, and 48 mM) were used, and the toxicity of Mn on PSII behavior in leaves of Ligustrum lucidum was investigated using in vivo chlorophyll fluorescence transients. Results showed that excessive Mn levels induced positive L- and K- bands. Variable fluorescence at 2 ms (VJ) and 30 ms (VI), absorption flux (ABS/RC), trapped energy flux (TRo/RC), and dissipated energy flux (DIo/RC) increased in Mn-treated leaves, whereas the performance index (PIABS), electron transport flux (ETo/RC), maximum quantum yield (φPo), quantum yield of electron transport (φEo), and probability that an electron moves further than QA- (ψo) decreased. Also, excessive Mn significantly decreased the net photosynthesis rate and increased intercellular CO2 concentration. The results indicated that Mn blocked the electron transfer from the donor side to the acceptor side in PSII, which might be associated with the accumulation of QA-, hence limiting the net photosynthetic rate.