Catalytic Stereoselective Synthesis of Highly Substituted Indanones via Tandem Nazarov Cyclization and Electrophilic Fluorination Trapping

Abstract

A new catalytic stereoselective tandem transformation via Nazarov cyclization/electrophilic fluorination has been accomplished. This sequence is efficiently catalyzed by a Cu(II) complex to afford fluorine-containing 1-indanone derivatives with two new stereocenters with high diastereoselectivity (trans/cis up to 49/1). Three examples of catalytic enantioselective tandem transformation are presented.

Asymmetric Nazarov cyclizations

“…Jun-An Ma and coworkers have described a tandem enantioselective Nazarov cyclization – electrophilic fluorination sequence that leads to fluoroindanones (eq 9). 13 Development of a tandem process introduces another element of complexity to the process. In Ma and coworkers' reaction, fluorination of the enolate represents the termination step of the process.…”

Stereoselective fluorination of methylenecyclopropanes with N-F reagents: A modular entry to γ-fluorohomoallylic sulfonimides and γ-fluorohomoallylic amides

“…In this regard, there exists an increasing demand for the efficient introduction of fluorine atom into olefin-containing compounds. Among the many methods used for the introduction of fluorine, electrophilic fluorination using N-F reagents has grown in popularity and applications to the selective fluorination of activated aromatics, alkenes, and enolates in recent years [12][13][14][15][16][17]. Despite increased use of these regents, no example on the reaction of electrophilic fluorinating agents with methylenecyclopropanes has been disclosed thus far.…”

Asymmetric electrocyclic reactions

“…31 In related work, Ma et al have developed a catalytic asymmetric tandem Nazarov cyclization-electrophilic fluorination (Scheme 10). 56 In this process, the direction of conrotation is catalystcontrolled (presumably via a model similar to that reported Scheme 6 Auxiliary-controlled Nazarov cyclizations.…”