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

Abstract

An oxocarbenium-olefin cross metathesis occurs during Brønsted acid catalyzed reactions of 1H-isochromene acetals with vinyl diazo compounds. Formally a carbonyl-alkene [2 + 2]-cyclization between isobenzopyrylium ions and the vinyl group of vinyl diazoesters, the retro-[2 + 2] cycloaddition produces a tethered alkene and a vinyl diazonium ion that, upon loss of dinitrogen, undergoes a highly selective carbocationic cascade rearrangements to diverse products whose formation is controlled by reactant substituents. Polysubstituted benzobicyclo[3.3.1]­oxocines, benzobicyclo[3.2.2]­oxepines, benzobicyclopropane, and naphthalenes are obtained in good to excellent yields and selectivities. Furthermore, isotopic tracer and control experiments shed light on the oxocarbenium-olefin metathesis/rearrangement process as well as on the origin of the interesting substituent-dependent selectivity.

Synthesis of Heterocycles by HNTf2-Catalyzed C–H Functionalization of Vinyldiazo Compounds with 3-Phenyl-3-hydroxyisoindolinone

“…5, 164.9, 151.8, 143.8, 136.5, 134.9, 132.7, 130.2, 129.5, 129.1, 129.0, 128.7, 128.4, 128.0, 127.8, 127.3, 127.0, 125.7, 124.0, 123.0, 67.0, 61.3, 14.6. 2 H),7.51 (t,J = 7.5 Hz,1 H),7 H),12 H),2 H),7.09 (t, J = 7.5 Hz, 1 H), 6.99-6.97 (comp, 2 H), 6.44 (d, J = 7.6 Hz, 1 H), 5.85 (s, 1 H), 5.71 (s, 1 H), 4.31-4.26 (comp, 4 H), 1.31-1.28 (comp, 6 H). 13 C NMR (125 MHz, CDCl 3 ):  = 169.…”

“…3 Meanwhile, their dipolar nature makes them susceptible to addition by different electrophilic reagents at the vinylogous position rather than the diazo carbon, affording diazonium ion intermediates that undergo substitution or migration reactions (Scheme 1a , path b). 4 Recently, we reported the HNTf 2 -catalyzed electrophilic addition of quinone oxonium ions from quinone ketals 5 and quinone imine ketals, 6 and isobenzopyrylium ions from 1 H ‑isochromene acetals 7 to the vinylogous carbon of vinyldiazo compounds 1 to form vinyldiazonium ion intermediates that result in the synthesis of substituted α-diazo esters and polycyclic compounds (Scheme 1b , path c). Using the stable Eschenmoser salt as the electrophile, an alternative C–H functionalization occurs at the γ-position of vinyl diazo compounds to form γ-substituted vinyldiazo esters (Scheme 1b , path d).…”

Triflamides and Triflimides: Synthesis and Applications

“…Triflimide 1 (Tf 2 NH) is used as a catalytic additive in the formation of C-C and Cheteroatom bonds, due to its strong acidity, as well as its good compatibility with various organic solvents [18]. It has been widely used as a Brønsted acid for the catalysis of Friedel-Crafts reactions [19][20][21][22][23][24] and cycloaddition reactions [25,26]. In addition, triflimide is used as a Brønsted acid, for example, to obtain various bis-arylated amides from vinyl azides in moderate to quantitative yields [27] or in the hydroalkylation of arylalkenes with activated alcohols [28].…”

Chiral Magnesium Complex-Catalyzed Asymmetric Cyclization of Vinyl Diazo Compounds with Phenol Derivatives via Noncarbene Pathways

“…First, due to the resonance nature of vinyl diazo compounds, they often act as dipolar reagents to react with electrophiles to generate diazo cation intermediates Int 1 and Int 2 , which are aligned for tandem electrophilic substitution/addition. − Second, the vinyl diazo compounds can serve as radical acceptors to react with electron-deficient radicals or radical cation species in a photoreaction system, where the vinyl radicals Int 3 are generally formed and could be trapped inter- or intramolecularly . In addition, a variety of cyclic products could be delivered through direct cycloaddition or annulation-rearrangement process, where the vinyl diazo compounds serve as two- or five-atom building units ( Int 4 and 5 ). , Despite these advancements, to the best of our knowledge, the asymmetric transformation of vinyl diazo compounds via noncarbene pathways has not been achieved so far.…”