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A catalytic enantioselective thioacetalization reaction has been developed. Various aldehydes react with unsymmetrical 1,3- or 1,2-dithiols to furnish chiral, enantioenriched thioacetals in excellent enantioselectivities upon treatment with a nitrated imidodiphosphoric acid catalyst. The transformation is assumed to proceed via a thionium ion intermediate. [ABSTRACT FROM AUTHOR]

The present study refers to the synthesis of cyclopentene subunits possessing three differentiable functional groups. A triphenylphosphine triggered one-pot Michael-intramolecular Wittig reaction between di-tert-butyl acetylenedicarboxylate and butanedione was made reproducible and scalable, delivering in good yield the desired tricarbonylated building block. Simple and selective transformations of this functionalized cyclopentene were performed. [ABSTRACT FROM AUTHOR]

Reported is the enantioselective total syntheses of mavacuran alkaloids, (+)-taberdivarine H, (+)-16-hydroxymethyl-pleiocarpamine, and (+)-16-epi-pleiocarpamine, and their postulated biosynthetic precursor 16-formyl-pleiocarpamine. This family of monoterpene indole alkaloids is a target of choice since some of its members are subunits of intricate bisindole alkaloids such as bipleiophylline. Inspired by the biosynthetic hypothesis, an oxidative coupling approach from the geissoschizine framework to form the N1-C16 bond was explored. Quaternization of the aliphatic nitrogen center was key to achieving the oxidative coupling induced by KHMDS/I 2 as it masks the nucleophilicity of the aliphatic nitrogen center and locks in the required cis conformation., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the first total synthesis of (-)-17-nor-excelsinidine, a zwitterionic monoterpene indole alkaloid that displays an unusual N4-C16 connection. Inspired by the postulated biosynthesis, we explored an oxidative coupling approach from the geissoschizine framework to forge the key ammonium-acetate connection. Two strategies allowed us to achieve this goal, namely an intramolecular nucleophilic substitution on a 16-chlorolactam with the N4 nitrogen atom or a direct I 2 -mediated N4-C16 oxidative coupling from the enolate of geissoschizine., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein we describe the development of a catalytic enantioselective alkynylogous Mukaiyama aldol reaction. The reaction is catalyzed by a newly designed chiral disulfonimide and delivers chiral allenoates in high yields and with excellent regio-, diastereo-, and enantioselectivity. Our process tolerates a broad range of aldehydes in combination with diverse alkynyl-substituted ketene acetals. The reaction products can be readily derivatized to furnish a variety of highly substituted enantiomerically enriched building blocks., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The development of an intramolecular rhodium(I)-catalyzed Pauson-Khand reaction of alkoxyallene-ynes with a proximal alkoxy group is reported. This reaction, in the presence of a [Rh(cycloocta-1,5-diene)Cl]2/propane-1,3-diylbis(diphenylphosphane) system under a CO atmosphere, constitutes a powerful tool for selectively accessing carbo- and heterobicyclo[5.3.0] frameworks featuring an enol ether moiety. Through this procedure, a straightforward access to guaiane skeletons with a tertiary hydroxy group at the C10 position was achieved., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)