Stereocontrolled Syntheses of Tetralone‐ and Naphthyl‐Type Lignans by a One‐Pot Oxidative [3,3] Rearrangement/Friedel–Crafts Arylation

Abstract

The development of a stereoselective one-pot oxidative [3,3] sigmatropic rearrangement/Friedel-Crafts arylation that provides enantioenriched benzhydryl compounds is reported. The utility of this new transformation is demonstrated by the concise synthesis of several tetralone- and naphthyl-type lignan natural products, many of which display anti-malarial activity.

A sterically encumbered photoredox catalyst enables the unified synthesis of the classical lignan family of natural products

“…Although not planned, this deoxygenation was welcomed, as early attempts of a global deoxygenation proved cumbersome. To complete the synthesis deoxygenation of 54 was achieved through in situ activation with MsCl followed by reduction with LiAlH 4 , providing (±)-galcatin ( 55 ) in 5 steps in an overall 33% yield 42. Reduction of 53 with LiAlH 4 gave diol 56 in 73% yield as a single regioisomer after flash chromatography.…”

Triflimide-catalyzed allylsilane annulations of benzylic alcohols for the divergent synthesis of indanes and tetralins

“…This outcome is consistent with related observations we had made during our previously reported synthesis of lignan natural products. 10 Use of silane 2c gave rise to compound 8ee that contains three contiguous stereocenters in high yield, but as a 2 : 1 mixture of diastereomers due to poor selectivity during cyclization to form the new quaternary stereocenter. A similar outcome was observed utilizing silane 2d to produce indane 8ff .…”

An Efficient Route to Isochromene Derivatives via Cascade Radical Cyclization and Radical‐Radical Coupling

“…Hydrolysis of the product afforded 1.35 g of the corresponding isochromenylethylamine 4 af in 94% yield. The amine was next protected with benzoyl chloride (95% yield) followed by Friedel‐Crafts cyclization by treating with 1.2 equiv. BF 3 ⋅ Et 2 O to lead to polycyclic amide 6 af in 81% yield (dr=9:1).…”