論文

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim An approach to cyclic nitrones from N-hydroxylactam derivatives is documented. The nucleophilic addition of an organolithium reagent to an N-OSEM [SEM=2-(trimethylsilyl)ethoxymethyl] lactam forms a five-membered chelated intermediate, which undergoes both elimination and deprotection to give a fully substituted nitrone in a one-pot process. When combined with the N-oxidation of easily available chiral lactams, this method becomes especially useful for the quick synthesis of chiral nitrones in enantio-pure form, enabling the concise total synthesis of cylindricine C.

© 2019 American Chemical Society. The asymmetric total synthesis of fasicularin is reported. The key to success is the use of a chiral N-alkoxyamide to control both reactivity and stereoselectivity. This functional group enables the aza-spirocyclization and the reductive Strecker reaction, which cannot be realized with an ordinary amide. In addition, use of the chiral alkoxy group establishes two consecutive stereocenters in the aza-spirocyclization through remote stereocontrol.

Copyright © 2018 American Chemical Society. An iridium-catalyzed reductive nucleophilic addition to secondary amides is reported. After the iridium-catalyzed reduction, the resulting imines can undergo the Strecker reaction, the Mannich reaction, allylation, and [3 + 2]-cycloaddition. The method shows high chemoselectivity in the presence of other functional groups such as methyl ester.

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Full details of a stereodivergent hydroboration of allenes are reported. While hydroboration of an allene with 9-BBN provided a thermodynamically stable (E)-allylic alcohol after oxidative work-up, the reaction of an identical allene with HB(Sia)2 (disiamylborane) formed a (Z)-allylic alcohol as the kinetic product. The developed conditions allowed for the synthesis of trisubstituted olefins in a highly stereoselective fashion, which is known to be challenging. The method was also applied to the stereodivergent synthesis of structural motifs such as skipped dienes and allylbenzenes, which are often embedded in biologically active natural products.