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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Stereoselective synthesis of spirocyclic ketones by Nazarov reaction
Cristina Prandi1, Annamaria Deagostino, Paolo Venturello
1Dipartimento di Chimica Generale ed Organica Applicata, Università di Torino, C. so Massimo D'Azeglio, 48, I-10125 Torino, Italy. cristina.prandi@unito.it
Abstract:
[reaction: see text] The Suzuki-Miyaura cross-coupling reaction between alpha-ethoxydienyl boronates and lactone-derived vinyl triflates affords functionalized 6-(1-ethoxy-1,3-butadienyl)dihydropyran derivatives that undergo a Nazarov electrocyclic reaction under mild acidic conditions to give functionalized spirocyclic ketones. The product distribution and the stereoselectivity of the process are strongly dependent on the substitution of both the alpha-ethoxydiene and dihydropyran moieties. High stereoselectivity is observed in the presence of a C2-substituent on the dihydropyran moiety. The results are explained in terms of transition state geometries.
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