Eco-friendly organocatalyst- and reagent-controlled selective construction of diverse and multifunctionalized 2-hydroxybenzophenone frameworks for potent UV-A/B filters by cascade benzannulation
作者:Muhammad Saeed Akhtar、Raju S. Thombal、Ramuel John Inductivo Tamargo、Won-Guen Yang、Sung Hong Kim、Yong Rok Lee
DOI:10.1039/d0gc01011a
日期:——
2-hydroxy-3′-formylbenzophenones and [4 + 2] cycloaddition for 2-hydroxybenzophenones. With this methodology, an unprecedented double benzannulation allows one-pot construction of diverse 7-(2′-hydroxybenzoyl)-2-naphthaldehydes via [3 + 3 + 4] cycloaddition. This protocol features a broad substrate scope, high functional-group tolerance, and operational simplicity in an environmentally benign green solvent
Base-Mediated Denitrogenative Sulfonylation/Benzannulation of Conjugated <i>N</i>-Sulfonylhydrazones with 3-Formylchromones for the Construction of Polyfunctionalized Biaryl Sulfones
作者:Rajeev Shrestha、Hari Datta Khanal、Peter Yuosef M. Rubio、Sonaimuthu Mohandoss、Yong Rok Lee
DOI:10.1021/acs.orglett.0c02724
日期:2020.10.2
of conjugated N-sulfonylhydrazones and 3-formylchromones for the synthesis of diverse biaryl sulfones is described. The approach facilitates new C–C and C–Sbondformation via the cascade diazo formation/Michael addition/ring opening/denitrogenative sulfonylation/intramolecular cycloaddition/dehydration and introduces diverse functional groups onto biaryl sulfones. The synthesized compounds are converted
and the allenoate zwitterion 2, generated by addition of phosphine to acetylenedicarboxylates, undergo a cascade reaction sequence involving an unprecedented [5+3] annulation followed by deoxygenative rearrangementleading to dihydropyridine-fused benzopyrones. Unusual electronic control by the N-substituents of 1 directs the annulation pathway, leading to two different ring-systems. nitrones - dipolar
Sc(OTf)<sub>3</sub>/BF<sub>3</sub>·OEt<sub>2</sub>-Catalyzed Annulation of 3-Formylchromones with Functionalized Alkenes: Access to Diverse 2-Hydroxybenzophenones
作者:Sabera Sultana、Peter Yuosef M. Rubio、Hari Datta Khanal、Yong Rok Lee
DOI:10.1021/acs.orglett.2c01538
日期:2022.6.24
ed annulation of 3-formylchromones with functionalized alkenes for the direct construction of 2-hydroxybenzophenones is described. Sc(OTf)3/BF3·OEt2 acts as a synergistic catalyst, providing rapid synthetic access to diversely and highly functionalized 2-hydroxybenzophenones. This reaction has excellent regio- and chemoselectivities and is suitable for late-stage functionalization. The reaction proceeds
DABCO‐Catalysed [3+2] Cyclization/Deformylation Cascade of
<i>p</i>
‐Quinols with 3‐Formylchromones: Access to Benzopyrone‐Fused Tetracyclic Ring Systems
The construction of benzopyrone-fused hydrobenzofuranones via DABCO-catalyzed [3+2] cyclization/deformylationcascade of p-quinols with 3-formylchromones is described. The reaction works under mild reaction conditions to provide the desired products in 53–90% yields with complete diastereoselectivities. In addition, an enantioselective version with 81% ee is also realized in the presence of Takemoto's