Structural complexity biases vegetation greenness measures.

Vegetation 'greenness' characterized by spectral vegetation indices (VIs) is an integrative measure of vegetation leaf abundance, biochemical properties and pigment composition. Surprisingly, satellite observations reveal that several major VIs over the US Corn Belt are higher than those over the Amazon rainforest, despite the forests having a greater leaf area. This contradicting pattern underscores the pressing need to understand the underlying drivers and their impacts to prevent misinterpretations.

Alkyl Carbazates for Electrochemical Deoxygenative Functionalization of Heteroarenes.

The C-O bond cleavage for activation of alcohols is synthetically useful and practically challenging. This work describes carbazate as a new type of electrochemically activated alkylating agent derived from ubiquitous alcohols for direct functionalization of heteroarenes under mild electrolytic conditions. The simple undivided cell at low oxidative potentials with carbon/platinum electrode set-ups offers excellent substrate tolerance, affording a variety of primary, secondary and tertiary alkyl-decorated heterocycles in good chemical yields.

Electrochemical Alkynyl/Alkenyl Migration for the Radical Difunctionalization of Alkenes.

An efficient electrochemical 1,2-sulfonylation/alkynylation of alkenes via radical 1,4-alkynyl migration of alkynyl-substituted tertiary alcohols is described, which used sodium sulfinates as sulfonyl sources affording the corresponding α-sulfonyl-β-alkynylated products in moderate to excellent yields. This electrochemical reaction proceeds smoothly without the use of any metal catalyst, additive and oxidant and thus represents a new and eco-friendly strategy for the difunctionalization of unactive olefins, and also the first example of the electrochemical distal radical migration reaction.

Visible light-induced C3-sulfonamidation of imidazopyridines with sulfamides.

A visible light-induced regioselective sulfonamidation of imidazo[1,2-a]pyridines was developed using sulfamides as the nitrogen sources and aqueous NaClO solution as the oxidant under mild conditions. With the imidazo[1,2-a]pyridines bearing various substituents, the reaction proceeded smoothly to furnish the C3-sulfonamidation products in moderate to good yields. The method was also suitable for the sulfonamidation of some other imidazoheterocycles.

Iron-Catalyzed Regioselective Alkoxycarbonylation of Imidazoheterocycles with Carbazates.

A regioselective alkoxycarbonylation of imidazoheterocycles using carbazates as ester group sources in DMSO was developed, in which an inexpensive FeCl2·4H2O was used as the catalyst and (NH4)2S2O8 was the oxidant. The reaction proceeded smoothly under an air atmosphere to give the 3-alkoxycarbonylated products in moderate to good yields.

Regioselective Fluorination of Imidazo[1,2-a]pyridines with Selectfluor in Aqueous Condition.

A regioselective synthesis of 3-fluorinated imidazo[1,2-a]pyridines using 1-chloromethyl-4-fluoro-1,4-diazoniabi cyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor) as the fluorinating reagent in aqueous condition is described.