Flash chemistry based on high-resolution reaction time control using flow microreactors enables chemical reactions that cannot be done in batch and serves as a powerful tool for laboratory synthesis of organic compounds and for production in chemical and pharmaceutical industries.

Hexapole helicenes 1, which contain six [5]helicene substructures, were synthesized by Pd-catalyzed [2+2+2]cycloadditions of aryne precursor 6. Among the possible 20 stereoisomers, which include ten pairs of enantiomers, HH-1 was obtained selectively. Density functional theory (DFT) calculations identified HH-1 as the second most stable isomer that quantitatively isomerizes under thermal conditions into the most stable isomer (HH-2). Both enantiomers of HH-2 can be separated by chiral HPLC. Single-crystal X-ray diffraction analyses revealed a saddle-like structure for (P,M,P,P,M,P) HH-1 and a propeller-like structure for (P,M,P,M,P,M) HH-2. Because of the helical assembly and the resulting steric repulsion, the structure of HH-1 is significantly distorted and exhibits the largest twisting angle reported so far (up to 35.7° per benzene unit). Electrochemical studies and DFT calculations indicated a narrow HOMO-LUMO gap on account of the extended π-system. Kinetic studies of the isomerization from HH-1 to HH-2 and the racemization of enantiomerically pure HH-2 were conducted based on H NMR spectroscopy, HPLC analysis, and DFT calculations.

Benzalacetone synthase (BSA) is a novel plant‐specific polyketide synthase that catalyzes a one step decarboxylative condensation of 4‐coumaroyl‐CoA with malonyl‐CoA to produce the C6–C4 skeleton of phenylbutanoids in higher plants. A cDNA encoding BAS was for the first time cloned and sequenced from rhubarb (Rheum palmatum), a medicinal plant rich in phenylbutanoids including pharmaceutically important phenylbutanone glucoside, lindleyin. The cDNA encoded a 42‐kDa protein that shares 60–75% amino‐acid sequence identity with other members of the CHS‐superfamily enzymes. Interestingly, R. palmatum BAS lacks the active‐site Phe215 residue (numbering in CHS) which has been proposed to help orient substrates and intermediates during the sequential condensation of 4‐coumaroyl‐CoA with malonyl‐CoA in CHS. On the other hand, the catalytic cysteine‐histidine dyad (Cys164–His303) in CHS is well conserved in BAS. A recombinant enzyme expressed in Escherichia coli efficiently afforded benzalacetone as a single product from 4‐coumaroyl‐CoA and malonyl‐CoA. Further, in contrast with CHS that showed broad substrate specificity toward aliphatic CoA esters, BAS did not accept hexanoyl‐CoA, isobutyryl‐CoA, isovaleryl‐CoA, and acetyl‐CoA as a substrate. Finally, besides the phenylbutanones in rhubarb, BAS has been proposed to play a crucial role for the construction of the C6–C4 moiety of a variety of natural products such as medicinally important gingerols in ginger plant.

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The novel 3-tert-benzotriazinyl radical carrying the trifluoromethyl group was synthesized and exhibited pure 1D ferromagnetic interaction in the columnar structure.