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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Synthesis of Curved Polycyclic Arenes Embedded with Oxepine and Thiepine Using Ring Expansion Strategy
Sheng Zhang1, Hidenori Matsuyama1, Itaru Nakamura2
1Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Abstract:
A tandem oxidative ring expansion of a six- to seven-membered ring was developed to construct a new class of negatively curved polycyclic arenes embedded with oxepine and thiepine, namely, dibenzo[b,f]phenanthro[9,10-d]oxepine (DBPO) and dibenzo[b,f]phenanthro[9,10-d]thiepine (DBPT), respectively. Mechanistic studies disclosed that an unexpected [4 + 2] cycloadduct formed between the alkene moiety of o-biphenyl-linked methylenexanthenes and o-chloranil serves as a radical cation or a dication equivalent that facilitates the FeCl3-mediated tandem ring expansion process.
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