Publications by authors named "Mario Kock"

The enantioselective synthesis of (-)-dihydroraputindole D is reported. The key step is the desymmetrizing benzoylation of a prochiral 1,3-diol employing Trost's ProPhenol catalyst system, which has been applied for the first time to a cyclic molecule carrying geminal hydroxymethyl groups. The cyclopenta[f]indoline system was assembled by Au(I)-catalyzed cyclization of an alkynylated indoline precursor.

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The first diastereoselective total synthesis of the bisindole alkaloid raputindole A is reported. After Au(I)-catalyzed assembly of the cyclopenta[ f]indole tricycle, it was possible to hydrogenate the indene double bond regio- and diastereoselectively through iridium catalysis, guided by a preinstalled hydroxy function. Attempted HWE reaction led to formal elimination of formaldehyde from an α-quaternary cyclopentane carbaldehyde, which was circumvented by Takai olefination.

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The first total synthesis of the bisindole alkaloid raputindole A from the rutaceous plant Raputia simulans is reported. The key step is a Au(I)-catalyzed cyclization that assembles the cyclopenta[f]indole tricycle from a 6-alkynylated indoline precursor. The isobutenyl side chain was installed by Suzuki-Miyaura cross-coupling, followed by a regioselective reduction employing LiDBB.

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The raputindoles from the rutaceous tree Raputia simulans share a cyclopenta[f]indole partial structure the synthesis of which is subject of this investigation. An efficient route to a series of 1,5-di(indol-6-yl)pentenones was developed via Mo/Au-catalyzed Meyer-Schuster rearrangement of tertiary propargylic alcohol precursors. However, none of the enones underwent the desired Nazarov cyclization to a cyclopenta[f]indole.

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