Optically active pyridine derivatives 2, 15, 18, 19, 21, 26, and 27 are obtained by enantioselective reduction of the corresponding ketones 5, 7, 11–13, 24, and 25 using the chiral borane reagent chlorodiisopinocampheylborane [(Ipc)2BCl]. Nickel(0)‐mediated coupling of bromopyridines 2, 15, and 31 gives C2‐symmetric 2,2′‐bipyridines (R,R)‐32, (R,R′)‐33, and (S,S)‐38, respectively, which form metal complexes with CoII, PdII, CuI, and AgI. Aryl‐substituted pyridines 26, and 39–41 are synthesized by palladium(0)‐catalyzed cross couplings of 2 and 15 with boronic acids 42–44.
COMMUNICATIONS 0.025 -0.1 u) confirmed the expected linear relationship (not shown, three experiments, p = 0.9984).The fluorescence reporters 1 and 2 are highly sensitive probes for detecting phosphodiesterase activity. Their use as test substrates not only allows detection of phosphodiesterase activity, but also phosphatase activity.
E.xperimental Section
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