The ionic liquids bearing an aromatic vinylic C–H moiety are not innocent during Pd-catalyzed cross-coupling reactions of aryl halides, since palladium-catalyzed direct C–H arylation of thiazolium and imidazolium ionic liquids competes.

Hydroxy-substituted sulfonic acid functionalized silica (HO-SAS) in combination with THF containing a small amount of water as a solvent proved to be a reliable system for the dehydration of allylic alcohols. This process generally caused dehydration within 1 min through a column reactor charged with HO-SAS. The flow dehydration was sequenced by flow hydrogenation, which resulted in the synthesis of pristane. A scalable flow synthesis of pristane was successfully performed and afforded 10 g of pristane after an operation of 2 h. We also performed dehydration and hydrogenation by using a mixed column of HO-SAS and 10 % Pd/C.

The Cover Feature shows the one-flow synthesis of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which involves flow [2+1] addition of C60 with diazoalkane and subsequent flow photoisomerization of the resulting fulleroid to PCBM by using a flow photoreactor in combination with a Na lamp. The two-step reactions proceeded within a residence time of 3 min, and a scalable synthesis of PCBM was achieved by continuous operation (0.79 g/3.3 h). More information can be found in the Communication by H. Yasuda, T. Fukuyama et al.

An efficient flow system was constructed for the synthesis of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM); the process involved flow [2+1] addition of C60 and subsequent flow photoisomerization of the resulting fulleroid to PCBM by using a flow photoreactor in combination with an Na lamp. With the present flow system, a scalable synthesis of PCBM (0.79 g/3.3 h) was achieved by continuous operation for 3.3 h.

A Cossy 5-exo-dig photocyclization of organohalides (X = Br, I) onto a C–C triple bond was studied using a flow photomicroreactor, which proceeded in a minute order of residence time. A deuterium labeling study supported the nonchain radical mechanism proposed by the Cossy group, in which a hydrogen source originates from a triethylamine cation radical. Scalable flow synthesis using a larger volume of flow reactor was also successful, providing 4 g of the product in high yield.

The generation of, and subsequent reactions with, 1-silyl-substituted organolithiums with CO was carried out using serially connected flow microreactors. The flow system proved to be quite useful for the carbonylation of silyl-substituted organolithiums under slightly pressurized conditions of CO, which was created conveniently by the use of a back-pressure regulator. This flow system, coupled with heating, accelerated the carbonylation reaction of 1-silyl-substituted organolithiums and allowed the stable silyl-substituted alkyllithium, 1,3-disilylallyllithium, which was not effective in a batch-flask reaction under a CO atmosphere, to participate in an efficient carbonylation reaction.

An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones.

Rhodium-catalyzed intramolecular C–H arylation of 2-aryloxybenzoic acids proceeded accompanied by decarbonylation to give dibenzofuran derivatives in high yields. The present reaction is widely applicable to substrates bearing various functionalities.

Carbonylation reactions, such as Heck, Sonogashira, and radical carbonylations, were successfully carried out in a “two-chamber reactor” where carbon monoxide was produced ex situ by the Morgan reaction (dehydration of formic acid by sulfuric acid). By a subsequent application in a microflow system using a “tube-in-tube” reactor where gas-permeable Teflon AF2400 was used as the inner tube, it is demonstrated that formic acid/sulfuric acid can be employed concomitantly with an amine base such as triethylamine in the Heck aminocarbonylation of aryl iodide.

The catalytic decarbonylation reaction of aliphatic carboxylic acids can be carried out in the presence of an iron complex, and it proceeds smoothly to give α-olefins with high selectivity.

Vaska’s complex, IrCl(CO)(PPh3)2, when combined with KI as an additive, served as an excellent catalyst for the decarbonylation of long-chain aliphatic carboxylic acids to give internal alkenes with high selectivity. On combination with KI and Ac2O as additives under controlled temperatures, decarbonylation proceeded to give terminal alkenes with high selectivity.

A novel [5+1] type carbonylative cycloaddition reaction has been developed using a Rh complex as catalyst. This reaction can convert readily available 3-acyloxy-1,4-enynes and CO to a wide range of functionalized resorcinols in good yields. A mechanism involving Rh-catalyzed cyclocarbonylation of 3-acyloxy-1,4-enynes accompanied by a 1,2-acyloxy shift is proposed for the present [5+1] type cycloaddition reaction.

The catalytic decarbonylation reaction of aliphatic carboxylic acids can be carried out in the presence of an iron complex, and it proceeds smoothly to give α-olefins with high selectivity.

A novel [5+1] type carbonylative cycloaddition reaction has been developed using a Rh complex as catalyst. This reaction can convert readily available 3-acyloxy-1,4-enynes and CO to a wide range of functionalized resorcinols in good yields. A mechanism involving Rh-catalyzed cyclocarbonylation of 3-acyloxy-1,4-enynes accompanied by a 1,2-acyloxy shift is proposed for the present [5+1] type cycloaddition reaction.