Benzannulation of isobenzopyryliums with electron-rich alkynes: a modular access to β-functionalized naphthalenes

Abstract

<p>Described here is a modular strategy for the rapid synthesis of β-functionalized electron-rich naphthalenes, a family of valuable molecules lacking general access previously. Our approach employs an intermolecular benzannulation of...</p>

Formal [4 + 4]-, [4 + 3]-, and [4 + 2]-cycloaddition reactions of donor–acceptor cyclobutenes, cyclopropenes and siloxyalkynes induced by Brønsted acid catalysis

“…with 2,4,6-collidine (1 equiv.) was reported, 18 and HNTf 2 was stated to be much less effective. To clarify this discrepancy, we carefully repeated these transformations ( 7ma and 7na ) and found that all starting materials are completely consumed in less than 10 min to deliver [4 + 2]-cycloaddition products in good yields.…”

Brønsted Acid Catalyzed Oxocarbenium-Olefin Metathesis/Rearrangements of 1H-Isochromene Acetals with Vinyl Diazo Compounds

“…Isobenzopyrylium species, which are generated by metal or acid catalysis, are examples of alternative electrophiles that could undergo reactions with vinyl diazo compounds. Generally, metal catalyzed [4 + 2]-cycloadditions occur between isobenzopyrilium salts and alkenes, affording 1-ketonyl-1,2-dihydronaphthalenes .…”

Asymmetric reactions involving isobenzopyrylium ion intermediates

“…The reported reactions included 1,2-nucleophilic addition, [4+2] cycloaddition, [3+2] cycloaddition and various cascade reactions. [37][38][39][40][41][42][43][44] The asymmetric transformations of isobenzopyrylium ions have been less explored. 45 This may be because the planar 10 π-electron aromatic structure of the isobenzopyrylium ion lacks an obvious coordination site for a chiral catalyst which is often crucial for achieving high stereoselectivity.…”