Aryne-Induced S_NAr/Dearylation Strategy for the Synthesis of Fluorinated Dibenzophospholes from Triarylphosphines via a P(V) Intermediate

Abstract

We report on a method for the synthesis of fluorinated dibenzophospholes using triarylphosphine via dearylative annulation with an aryne. This intermolecular annulation allows the preparation of a variety of fluorinated dibenzophospholes from simple building blocks. The key to the success of this dearylative annulation is the formation of a five-coordinated tetraarylfluorophosphorane. In this work, we successfully synthesized stable tetraarylfluorophosphorane, the structure of which was unambiguously determined by X-ray crystallography.

Aryne Annulations for the Synthesis of Carbocycles and Heterocycles: An Updated Review

“…In 2020, Tobisu and co-workers introduced a unique fluorinated dibenzophospholes following a dearylative annulation strategy employing aryne 1 and triarylphosphine derivative 179 (Scheme 62). 54 The main attraction of this protocol laid in the successful synthesis of stable five-coordinated tetraarylfluorophosphorane 180. This methodology follows a simple fluoride induced in situ generation of aryne accompanying the annulation with triarylphosphine in CH3CN/H2O.…”

Reactions of Organophosphorus Compounds with Arynes: Reactivity and Mechanism

“…Inspired by Wittig's ground‐breaking report, Tobisu group recently developed a transition‐metal‐free dearylative annulation reaction of arynes and tri( o ‐fluoroaryl)phosphine (Scheme 8). [19] This protocol allowed the facile synthesis of a variety of fluorinated dibenzophospholes at room temperature in moderate yields. In this case, the formation of phosphonium salt intermediates could further reduce the electron density of fluorinated aromatic rings.…”

Acylalkylation of Arynes Generated from o-Iodoaryl Triflates with Hydrosilanes and Cesium Fluoride

“…Aryne chemistry realizing unique transformations has attracted a broad range of chemists in synthetic organic chemistry, pharmaceutical sciences, and materials chemistry. − The recent remarkable progress of synthetic methods through aryne intermediates generated from a range of precursors such as o -silylaryl triflates and o -iodoaryl triflates has significantly expanded the synthesizable arenes (Figure A). In particular, insertion reactions including the acylalkylation of arynes have allowed us to prepare various multisubstituted arenes from o -silylaryl triflates (Figure B) .…”

“…A wide variety of difunctionalizations of aryne intermediates through insertion reactions have been achieved using o -silylaryl triflates as aryne precursors with fluoride sources. − In sharp contrast, only a few insertion reactions using o -iodoaryl triflates as aryne precursors have been reported so far because nucleophilic activators such as n -butyllithium react with arynophiles bearing electrophilic moieties. Over the course of our synthetic aryne chemistry using various o -iodoaryl triflates, we attempted the acylalkylation of benzyne with 1,3-diketone 2a by the treatment of o -iodophenyl triflate ( 1a ) with n -butyllithium, i -propylmagnesium chloride, or (trimethylsilyl)­methylmagnesium chloride (Figure D).…”